blocks|key|1259252|text|不久前，我做了一个函数来实现这个目的：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1259253|function+getAge(birthDate)+{
++var+now+=+new+Date();

++function+isLeap(year)+{
++++return+year+%25+4+==+0+&&+(year+%25+100+!=+0+%7C%7C+year+%25+400+==+0);
++}

++//+days+since+the+birthdate++++
++var+days+=+Math.floor((now.getTime()+-+birthDate.getTime())/1000/60/60/24);
++var+age+=+0;
++//+iterate+the+years
++for+(var+y+=+birthDate.getFullYear();+y+<=+now.getFullYear();+y%2B%2B){
++++var+daysInYear+=+isLeap(y)+?+366+:+365;
++++if+(days+>=+daysInYear){
++++++days+-=+daysInYear;
++++++age%2B%2B;
++++++//+increment+the+age+only+if+there+are+available+enough+days+for+the+year.
++++}
++}
++return+age;
}|code-block|syntax|javascript|1259254|它接受一个Date对象作为输入，因此您需要解析'YYYYMMDD'格式的日期字符串：|offset|length|style|CODE|1259255|var+birthDateStr+=+'19840831',
++++parts+=+birthDateStr.match(/(\d{4})(\d{2})(\d{2})/),
++++dateObj+=+new+Date(parts[1],+parts[2]-1,+parts[3]);+//+months+0-based!

getAge(dateObj);+//+26|1259256|entityMap^0|0|0|N|A|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|S|8|@$I|T|J|U|K|L]]|9|@]|A|$]]|$1|M|3|N|5|D|7|V|8|@]|9|@]|A|$E|F]]|$1|O|3|-4|5|6|7|W|8|@]|9|@]|A|$]]]|P|$]]

Some time ago I made a function with that purpose:

<pre><code>function getAge(birthDate) {
 var now = new Date();

 function isLeap(year) {
 return year % 4 == 0 &amp;&amp; (year % 100 != 0 || year % 400 == 0);
 }

 // days since the birthdate 
 var days = Math.floor((now.getTime() - birthDate.getTime())/1000/60/60/24);
 var age = 0;
 // iterate the years
 for (var y = birthDate.getFullYear(); y &lt;= now.getFullYear(); y++){
 var daysInYear = isLeap(y) ? 366 : 365;
 if (days &gt;= daysInYear){
 days -= daysInYear;
 age++;
 // increment the age only if there are available enough days for the year.
 }
 }
 return age;
}
</code></pre>

It takes a Date object as input, so you need to parse the <code>'YYYYMMDD'</code> formatted date string:

<pre><code>var birthDateStr = '19840831',
 parts = birthDateStr.match(/(\d{4})(\d{2})(\d{2})/),
 dateObj = new Date(parts[1], parts[2]-1, parts[3]); // months 0-based!

getAge(dateObj); // 26
</code></pre>

blocks|key|3480244|text|为了测试生日是否已经过去，我定义了一个辅助函数Date.prototype.getDoY，它可以有效地返回一年中的日期。剩下的就不言自明了。|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|3480245|Date.prototype.getDoY+=+function()+{
++++var+onejan+=+new+Date(this.getFullYear(),+0,+1);
++++return+Math.floor(((this+-+onejan)+/+86400000)+%2B+1);
};

function+getAge(birthDate)+{
++++function+isLeap(year)+{
++++++++return+year+%25+4+==+0+&&+(year+%25+100+!=+0+%7C%7C+year+%25+400+==+0);
++++}

++++var+now+=+new+Date(),
++++++++age+=+now.getFullYear()+-+birthDate.getFullYear(),
++++++++doyNow+=+now.getDoY(),
++++++++doyBirth+=+birthDate.getDoY();

++++//+normalize+day-of-year+in+leap+years
++++if+(isLeap(now.getFullYear())+&&+doyNow+>+58+&&+doyBirth+>+59)
++++++++doyNow--;

++++if+(isLeap(birthDate.getFullYear())+&&+doyNow+>+58+&&+doyBirth+>+59)
++++++++doyBirth--;

++++if+(doyNow+<=+doyBirth)
++++++++age--;++//+birthday+not+yet+passed+this+year,+so+-1

++++return+age;
};

var+myBirth+=+new+Date(2001,+6,+4);
console.log(getAge(myBirth));|code-block|syntax|javascript|3480246|entityMap^0|N|L|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

To test whether the birthday already passed or not, I define a helper function <code>Date.prototype.getDoY</code>, which effectively returns the day number of the year. The rest is pretty self-explanatory.

<pre><code>Date.prototype.getDoY = function() {
 var onejan = new Date(this.getFullYear(), 0, 1);
 return Math.floor(((this - onejan) / 86400000) + 1);
};

function getAge(birthDate) {
 function isLeap(year) {
 return year % 4 == 0 &amp;&amp; (year % 100 != 0 || year % 400 == 0);
 }

 var now = new Date(),
 age = now.getFullYear() - birthDate.getFullYear(),
 doyNow = now.getDoY(),
 doyBirth = birthDate.getDoY();

 // normalize day-of-year in leap years
 if (isLeap(now.getFullYear()) &amp;&amp; doyNow &gt; 58 &amp;&amp; doyBirth &gt; 59)
 doyNow--;

 if (isLeap(birthDate.getFullYear()) &amp;&amp; doyNow &gt; 58 &amp;&amp; doyBirth &gt; 59)
 doyBirth--;

 if (doyNow &lt;= doyBirth)
 age--; // birthday not yet passed this year, so -1

 return age;
};

var myBirth = new Date(2001, 6, 4);
console.log(getAge(myBirth));
</code></pre>

blocks|key|2006705|text|function+age()
{
++++var+birthdate+=+$j('#birthDate').val();+//+in+++"mm/dd/yyyy"+format
++++var+senddate+=+$j('#expireDate').val();+//+in+++"mm/dd/yyyy"+format
++++var+x+=+birthdate.split("/");++++
++++var+y+=+senddate.split("/");
++++var+bdays+=+x[1];
++++var+bmonths+=+x[0];
++++var+byear+=+x[2];
++++//alert(bdays);
++++var+sdays+=+y[1];
++++var+smonths+=+y[0];
++++var+syear+=+y[2];
++++//alert(sdays);

++++if(sdays+<+bdays)
++++{
++++++++sdays+=+parseInt(sdays)+%2B+30;
++++++++smonths+=+parseInt(smonths)+-+1;
++++++++//alert(sdays);
++++++++var+fdays+=+sdays+-+bdays;
++++++++//alert(fdays);
++++}
++++else{
++++++++var+fdays+=+sdays+-+bdays;
++++}

++++if(smonths+<+bmonths)
++++{
++++++++smonths+=+parseInt(smonths)+%2B+12;
++++++++syear+=+syear+-+1;
++++++++var+fmonths+=+smonths+-+bmonths;
++++}
++++else
++++{
++++++++var+fmonths+=+smonths+-+bmonths;
++++}

++++var+fyear+=+syear+-+byear;
++++document.getElementById('patientAge').value+=+fyear%2B'+years+'%2Bfmonths%2B'+months+'%2Bfdays%2B'+days';
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|2006706|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>function age()
{
 var birthdate = $j('#birthDate').val(); // in "mm/dd/yyyy" format
 var senddate = $j('#expireDate').val(); // in "mm/dd/yyyy" format
 var x = birthdate.split("/"); 
 var y = senddate.split("/");
 var bdays = x[1];
 var bmonths = x[0];
 var byear = x[2];
 //alert(bdays);
 var sdays = y[1];
 var smonths = y[0];
 var syear = y[2];
 //alert(sdays);

 if(sdays &lt; bdays)
 {
 sdays = parseInt(sdays) + 30;
 smonths = parseInt(smonths) - 1;
 //alert(sdays);
 var fdays = sdays - bdays;
 //alert(fdays);
 }
 else{
 var fdays = sdays - bdays;
 }

 if(smonths &lt; bmonths)
 {
 smonths = parseInt(smonths) + 12;
 syear = syear - 1;
 var fmonths = smonths - bmonths;
 }
 else
 {
 var fmonths = smonths - bmonths;
 }

 var fyear = syear - byear;
 document.getElementById('patientAge').value = fyear+' years '+fmonths+' months '+fdays+' days';
}
</code></pre>

blocks|key|1256977|text|尝尝这个。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1256978|function+getAge(dateString)+{
++++var+today+=+new+Date();
++++var+birthDate+=+new+Date(dateString);
++++var+age+=+today.getFullYear()+-+birthDate.getFullYear();
++++var+m+=+today.getMonth()+-+birthDate.getMonth();
++++if+(m+<+0+%7C%7C+(m+===+0+&&+today.getDate()+<+birthDate.getDate()))+{
++++++++age--;
++++}
++++return+age;
}|code-block|syntax|javascript|1256979|我认为在您的代码中唯一看起来粗糙的是substr部分。|offset|length|style|CODE|1256980|小提琴：http://jsfiddle.net/codeandcloud/n33RJ/|BOLD|1256981|entityMap|0|LINK|mutability|MUTABLE|url|http://jsfiddle.net/codeandcloud/n33RJ/^0|0|0|I|6|0|0|3|4|13|0|0^^$0|@$1|2|3|4|5|6|7|X|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|Y|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Z|8|@$I|10|J|11|K|L]]|9|@]|A|$]]|$1|M|3|N|5|6|7|12|8|@$I|13|J|14|K|O]]|9|@$I|15|J|16|1|17]]|A|$]]|$1|P|3|-4|5|6|7|18|8|@]|9|@]|A|$]]]|Q|$R|$5|S|T|U|A|$V|W]]]]

Try this.

<pre><code>function getAge(dateString) {
 var today = new Date();
 var birthDate = new Date(dateString);
 var age = today.getFullYear() - birthDate.getFullYear();
 var m = today.getMonth() - birthDate.getMonth();
 if (m &lt; 0 || (m === 0 &amp;&amp; today.getDate() &lt; birthDate.getDate())) {
 age--;
 }
 return age;
}
</code></pre>

I believe the only thing that looked crude on your code was the <code>substr</code> part.

Fiddle: <a href="http://jsfiddle.net/codeandcloud/n33RJ/" rel="noreferrer">http://jsfiddle.net/codeandcloud/n33RJ/</a>

blocks|key|2006735|text|这是我修改后的尝试(使用传递给函数的字符串，而不是date对象)：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2006736|function+calculateAge(dobString)+{
++++var+dob+=+new+Date(dobString);
++++var+currentDate+=+new+Date();
++++var+currentYear+=+currentDate.getFullYear();
++++var+birthdayThisYear+=+new+Date(currentYear,+dob.getMonth(),+dob.getDate());
++++var+age+=+currentYear+-+dob.getFullYear();

++++if(birthdayThisYear+>+currentDate)+{
++++++++age--;
++++}

++++return+age;
}|code-block|syntax|javascript|2006737|和用法：|2006738|console.log(calculateAge('1980-01-01'));|2006739|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

This is my amended attempt (with a string passed in to function instead of a date object):

<pre><code>function calculateAge(dobString) {
 var dob = new Date(dobString);
 var currentDate = new Date();
 var currentYear = currentDate.getFullYear();
 var birthdayThisYear = new Date(currentYear, dob.getMonth(), dob.getDate());
 var age = currentYear - dob.getFullYear();

 if(birthdayThisYear &gt; currentDate) {
 age--;
 }

 return age;
}
</code></pre>

And usage:

<pre><code>console.log(calculateAge('1980-01-01'));
</code></pre>

blocks|key|4892065|text|我只需要自己写这个函数-公认的答案是相当好的，但IMO可以使用一些清理。这需要一个unix时间戳给道布，因为这是我的需求，但可以很快调整为使用字符串：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4892066|var+getAge+=+function(dob)+{
++++var+measureDays+=+function(dateObj)+{
++++++++++++return+31*dateObj.getMonth()%2BdateObj.getDate();
++++++++},
++++++++d+=+new+Date(dob*1000),
++++++++now+=+new+Date();

++++return+now.getFullYear()+-+d.getFullYear()+-+(measureDays(now)+<+measureDays(d));
}|code-block|syntax|javascript|4892067|请注意，我在measureDays函数中使用了一个单一值31。计算所关心的是“一年中的某一天”是时间戳的单调递增度量。|4892068|如果使用javascript时间戳或字符串，显然你会想去掉1000的系数。|4892069|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|P|8|@]|9|@]|A|$]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

I just had to write this function for myself - the accepted answer is fairly good but IMO could use some cleanup. This takes a unix timestamp for dob because that was my requirement but could be quickly adapted to use a string: 

<pre><code>var getAge = function(dob) {
 var measureDays = function(dateObj) {
 return 31*dateObj.getMonth()+dateObj.getDate();
 },
 d = new Date(dob*1000),
 now = new Date();

 return now.getFullYear() - d.getFullYear() - (measureDays(now) &lt; measureDays(d));
}
</code></pre>

Notice I've used a flat value of 31 in my measureDays function. All the calculation cares about is that the "day-of-year" be a monotonically increasing measure of the timestamp.

If using a javascript timestamp or string, obviously you'll want to remove the factor of 1000.

blocks|key|4892095|text|这是我的解决方案，只需传入一个可解析的日期：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4892096|function+getAge(birth)+{
++ageMS+=+Date.parse(Date())+-+Date.parse(birth);
++age+=+new+Date();
++age.setTime(ageMS);
++ageYear+=+age.getFullYear()+-+1970;

++return+ageYear;

++//+ageMonth+=+age.getMonth();+//+Accurate+calculation+of+the+month+part+of+the+age
++//+ageDay+=+age.getDate();++++//+Approximate+calculation+of+the+day+part+of+the+age
}|code-block|syntax|javascript|4892097|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Here's my solution, just pass in a parseable date:

<pre><code>function getAge(birth) {
 ageMS = Date.parse(Date()) - Date.parse(birth);
 age = new Date();
 age.setTime(ageMS);
 ageYear = age.getFullYear() - 1970;

 return ageYear;

 // ageMonth = age.getMonth(); // Accurate calculation of the month part of the age
 // ageDay = age.getDate(); // Approximate calculation of the day part of the age
}
</code></pre>

blocks|key|2002484|text|我知道这是一个非常古老的线程，但我想把我写的这个实现放在这个实现中，以便找到我认为更准确的年龄。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2002485|var+getAge+=+function(year,month,date){
++++var+today+=+new+Date();
++++var+dob+=+new+Date();
++++dob.setFullYear(year);
++++dob.setMonth(month-1);
++++dob.setDate(date);
++++var+timeDiff+=+today.valueOf()+-+dob.valueOf();
++++var+milliInDay+=+24*60*60*1000;
++++var+noOfDays+=+timeDiff+/+milliInDay;
++++var+daysInYear+=+365.242;
++++return++(+noOfDays+/+daysInYear+)+;
}|code-block|syntax|javascript|2002486|当然，您可以对其进行调整，以适应获取参数的其他格式。希望这对寻找更好的解决方案的人有所帮助。|2002487|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

I know this is a very old thread but I wanted to put in this implementation that I wrote for finding the age which I believe is much more accurate. 

<pre><code>var getAge = function(year,month,date){
 var today = new Date();
 var dob = new Date();
 dob.setFullYear(year);
 dob.setMonth(month-1);
 dob.setDate(date);
 var timeDiff = today.valueOf() - dob.valueOf();
 var milliInDay = 24*60*60*1000;
 var noOfDays = timeDiff / milliInDay;
 var daysInYear = 365.242;
 return ( noOfDays / daysInYear ) ;
}
</code></pre>

Ofcourse you could adapt this to fit in other formats of getting the parameters. Hope this helps someone looking for a better solution.

blocks|key|4892151|text|替代解决方案，因为为什么不：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4892152|function+calculateAgeInYears+(date)+{
++++var+now+=+new+Date();
++++var+current_year+=+now.getFullYear();
++++var+year_diff+=+current_year+-+date.getFullYear();
++++var+birthday_this_year+=+new+Date(current_year,+date.getMonth(),+date.getDate());
++++var+has_had_birthday_this_year+=+(now+>=+birthday_this_year);

++++return+has_had_birthday_this_year
++++++++?+year_diff
++++++++:+year_diff+-+1;
}|code-block|syntax|javascript|4892153|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Alternate solution, because why not:

<pre><code>function calculateAgeInYears (date) {
 var now = new Date();
 var current_year = now.getFullYear();
 var year_diff = current_year - date.getFullYear();
 var birthday_this_year = new Date(current_year, date.getMonth(), date.getDate());
 var has_had_birthday_this_year = (now &gt;= birthday_this_year);

 return has_had_birthday_this_year
 ? year_diff
 : year_diff - 1;
}
</code></pre>

blocks|key|1257099|text|我检查了前面显示的示例，它们并不是在所有情况下都有效，因此我做了一个自己的脚本。我对此进行了测试，它工作得很完美。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1257100|function+getAge(birth)+{
+++var+today+=+new+Date();
+++var+curr_date+=+today.getDate();
+++var+curr_month+=+today.getMonth()+%2B+1;
+++var+curr_year+=+today.getFullYear();

+++var+pieces+=+birth.split('/');
+++var+birth_date+=+pieces[0];
+++var+birth_month+=+pieces[1];
+++var+birth_year+=+pieces[2];

+++if+(curr_month+==+birth_month+&&+curr_date+>=+birth_date)+return+parseInt(curr_year-birth_year);
+++if+(curr_month+==+birth_month+&&+curr_date+<+birth_date)+return+parseInt(curr_year-birth_year-1);
+++if+(curr_month+>+birth_month)+return+parseInt(curr_year-birth_year);
+++if+(curr_month+<+birth_month)+return+parseInt(curr_year-birth_year-1);
}

var+age+=+getAge('18/01/2011');
alert(age);|code-block|syntax|javascript|1257101|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

I've checked the examples showed before and they didn't worked in all cases, and because of this i made a script of my own. I tested this, and it works perfectly.

<pre><code>function getAge(birth) {
 var today = new Date();
 var curr_date = today.getDate();
 var curr_month = today.getMonth() + 1;
 var curr_year = today.getFullYear();

 var pieces = birth.split('/');
 var birth_date = pieces[0];
 var birth_month = pieces[1];
 var birth_year = pieces[2];

 if (curr_month == birth_month &amp;&amp; curr_date &gt;= birth_date) return parseInt(curr_year-birth_year);
 if (curr_month == birth_month &amp;&amp; curr_date &lt; birth_date) return parseInt(curr_year-birth_year-1);
 if (curr_month &gt; birth_month) return parseInt(curr_year-birth_year);
 if (curr_month &lt; birth_month) return parseInt(curr_year-birth_year-1);
}

var age = getAge('18/01/2011');
alert(age);
</code></pre>

blocks|key|2002540|text|function+getAge(dateString)+{

++++var+dates+=+dateString.split("-");
++++var+d+=+new+Date();

++++var+userday+=+dates[0];
++++var+usermonth+=+dates[1];
++++var+useryear+=+dates[2];

++++var+curday+=+d.getDate();
++++var+curmonth+=+d.getMonth()%2B1;
++++var+curyear+=+d.getFullYear();

++++var+age+=+curyear+-+useryear;

++++if((curmonth+<+usermonth)+%7C%7C+(+(curmonth+==+usermonth)+&&+curday+<+userday+++)){

++++++++age--;

++++}

++++return+age;
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|2002541|要获取输入欧洲日期的时间，请执行以下操作：|unstyled|2002542|getAge('16-03-1989')|2002543|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|L|8|@]|9|@]|A|$]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$B|C]]|$1|I|3|-4|5|F|7|N|8|@]|9|@]|A|$]]]|J|$]]

<pre><code>function getAge(dateString) {

 var dates = dateString.split("-");
 var d = new Date();

 var userday = dates[0];
 var usermonth = dates[1];
 var useryear = dates[2];

 var curday = d.getDate();
 var curmonth = d.getMonth()+1;
 var curyear = d.getFullYear();

 var age = curyear - useryear;

 if((curmonth &lt; usermonth) || ( (curmonth == usermonth) &amp;&amp; curday &lt; userday )){

 age--;

 }

 return age;
}
</code></pre>

To get the age when european date has entered:

<pre><code>getAge('16-03-1989')
</code></pre>

blocks|key|1257135|text|重要提示:此答案不能提供100%25准确的答案，根据日期的不同，可能会有大约10-20个小时的偏差。|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|1257136|1257137|没有更好的解决方案(至少在这些答案中没有)。--纳维恩|blockquote|1257138|1257139|1257140|当然，我忍不住要接受挑战，制作一个比目前公认的解决方案更快、更短的生日计算器。我的解决方案的要点是，数学运算速度很快，所以我们不使用分支和日期模型javascript来计算解决方案，而是使用奇妙的数学运算。|1257141|答案看起来像这样，运行速度比纳维恩快65%25，而且更短：|1257142|function+calcAge(dateString)+{
++var+birthday+=+%2Bnew+Date(dateString);
++return+~~((Date.now()+-+birthday)+/+(31557600000));
}|code-block|syntax|javascript|1257143|神奇的数字:+31557600000是24+*+3600+*+365.25+*+1000，这是一年的长度，一年的长度是365天6小时，也就是0.25天。最后我给出了最终年龄的结果。|1257144|以下是基准测试：http://jsperf.com/birthday-calculation|1257145|要支持OP的数据格式，您可以替换%2Bnew+Date(dateString);|CODE|1257146|使用%2Bnew+Date(d.substr(0,+4),+d.substr(4,+2)-1,+d.substr(6,+2));|1257147|如果你能想出更好的解决方案，请分享！:-)|1257148|entityMap|0|LINK|mutability|MUTABLE|url|http://jsperf.com/birthday-calculation^0|0|1C|0|0|0|0|0|0|0|0|0|8|12|0|0|G|M|0|2|1O|0|0^^$0|@$1|2|3|4|5|6|7|1D|8|@$9|1E|A|1F|B|C]]|D|@]|E|$]]|$1|F|3|-4|5|6|7|1G|8|@]|D|@]|E|$]]|$1|G|3|H|5|I|7|1H|8|@]|D|@]|E|$]]|$1|J|3|-4|5|6|7|1I|8|@]|D|@]|E|$]]|$1|K|3|-4|5|6|7|1J|8|@]|D|@]|E|$]]|$1|L|3|M|5|6|7|1K|8|@]|D|@]|E|$]]|$1|N|3|O|5|6|7|1L|8|@]|D|@]|E|$]]|$1|P|3|Q|5|R|7|1M|8|@]|D|@]|E|$S|T]]|$1|U|3|V|5|6|7|1N|8|@]|D|@]|E|$]]|$1|W|3|X|5|6|7|1O|8|@]|D|@$9|1P|A|1Q|1|1R]]|E|$]]|$1|Y|3|Z|5|6|7|1S|8|@$9|1T|A|1U|B|10]]|D|@]|E|$]]|$1|11|3|12|5|6|7|1V|8|@$9|1W|A|1X|B|10]]|D|@]|E|$]]|$1|13|3|14|5|6|7|1Y|8|@]|D|@]|E|$]]|$1|15|3|-4|5|6|7|1Z|8|@]|D|@]|E|$]]]|16|$17|$5|18|19|1A|E|$1B|1C]]]]

Important: This answer doesn't provide an 100% accurate answer, it is off by around 10-20 hours depending on the date. 

<blockquote>
 There are no better solutions ( not in these answers anyway ). - naveen
</blockquote>

I of course couldn't resist the urge to take up the challenge and make a faster and shorter birthday calculator than the current accepted solution.
The main point for my solution, is that math is fast, so instead of using branching, and the date model javascript provides to calculate a solution we use the wonderful math

The answer looks like this, and runs ~65% faster than naveen's plus it's much shorter:

<pre><code>function calcAge(dateString) {
 var birthday = +new Date(dateString);
 return ~~((Date.now() - birthday) / (31557600000));
}
</code></pre>

The magic number: 31557600000 is 24 * 3600 * 365.25 * 1000
Which is the length of a year, the length of a year is 365 days and 6 hours which is 0.25 day. In the end i floor the result which gives us the final age.

Here is the benchmarks: <a href="http://jsperf.com/birthday-calculation" rel="noreferrer">http://jsperf.com/birthday-calculation</a>

To support OP's data format you can replace <code>+new Date(dateString);</code> 
 with <code>+new Date(d.substr(0, 4), d.substr(4, 2)-1, d.substr(6, 2));</code>

If you can come up with a better solution please share! :-)

blocks|key|4892318|text|这是我能想到的最简单、最准确的解决方案：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4892319|Date.prototype.getAge+=+function+(date)+{
++++if+(!date)+date+=+new+Date();
++++return+~~((date.getFullYear()+%2B+date.getMonth()+/+100
++++%2B+date.getDate()+/+10000)+-+(this.getFullYear()+%2B+
++++this.getMonth()+/+100+%2B+this.getDate()+/+10000));
}|code-block|syntax|javascript|4892320|这是一个示例，它将考虑一年的Feb+29+->+Feb+28。|4892321|Date.prototype.getAge+=+function+(date)+{
++++if+(!date)+date+=+new+Date();
++++var+feb+=+(date.getMonth()+==+1+%7C%7C+this.getMonth()+==+1);
++++return+~~((date.getFullYear()+%2B+date.getMonth()+/+100+%2B+
++++++++(feb+&&+date.getDate()+==+29+?+28+:+date.getDate())
++++++++/+10000)+-+(this.getFullYear()+%2B+this.getMonth()+/+100+%2B+
++++++++(feb+&&+this.getDate()+==+29+?+28+:+this.getDate())+
++++++++/+10000));
}|4892322|它甚至适用于负年龄！|4892323|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|Q|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|R|8|@]|9|@]|A|$E|F]]|$1|K|3|L|5|6|7|S|8|@]|9|@]|A|$]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

Here's the simplest, most accurate solution I could come up with:

<pre><code>Date.prototype.getAge = function (date) {
 if (!date) date = new Date();
 return ~~((date.getFullYear() + date.getMonth() / 100
 + date.getDate() / 10000) - (this.getFullYear() + 
 this.getMonth() / 100 + this.getDate() / 10000));
}
</code></pre>

And here is a sample that will consider Feb 29 -> Feb 28 a year.

<pre><code>Date.prototype.getAge = function (date) {
 if (!date) date = new Date();
 var feb = (date.getMonth() == 1 || this.getMonth() == 1);
 return ~~((date.getFullYear() + date.getMonth() / 100 + 
 (feb &amp;&amp; date.getDate() == 29 ? 28 : date.getDate())
 / 10000) - (this.getFullYear() + this.getMonth() / 100 + 
 (feb &amp;&amp; this.getDate() == 29 ? 28 : this.getDate()) 
 / 10000));
}
</code></pre>

It even works with negative age!

blocks|key|3480751|text|我更倾向于可读性：|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|3480752|function+_calculateAge(birthday)+{+//+birthday+is+a+date
++++var+ageDifMs+=+Date.now()+-+birthday.getTime();
++++var+ageDate+=+new+Date(ageDifMs);+//+miliseconds+from+epoch
++++return+Math.abs(ageDate.getUTCFullYear()+-+1970);
}|code-block|syntax|javascript|3480753|免责声明：这也有精度问题，所以这也不能完全信任。它可以关闭几个小时，在某些年份，或在夏令时(取决于时区)。|3480754|相反，如果精确度非常重要，我会建议使用库。另外，@Naveens+post可能是最准确的，因为它不依赖于一天中的时间。|CODE|3480755|3480756|entityMap|0|LINK|mutability|MUTABLE|url|https://stackoverflow.com/a/7091965/1044856^0|0|9|0|0|0|5|0|O|D|O|D|0|0|0^^$0|@$1|2|3|4|5|6|7|Y|8|@$9|Z|A|10|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|11|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|12|8|@$9|13|A|14|B|C]]|D|@]|E|$]]|$1|M|3|N|5|6|7|15|8|@$9|16|A|17|B|O]]|D|@$9|18|A|19|1|1A]]|E|$]]|$1|P|3|-4|5|6|7|1B|8|@]|D|@]|E|$]]|$1|Q|3|-4|5|6|7|1C|8|@]|D|@]|E|$]]]|R|$S|$5|T|U|V|E|$W|X]]]]

I would go for readability:
<pre><code>function _calculateAge(birthday) { // birthday is a date
 var ageDifMs = Date.now() - birthday.getTime();
 var ageDate = new Date(ageDifMs); // miliseconds from epoch
 return Math.abs(ageDate.getUTCFullYear() - 1970);
}
</code></pre>
Disclaimer: This also has precision issues, so this cannot be completely trusted either. It can be off by a few hours, on some years, or during daylight saving (depending on timezone).
Instead I would recommend using a library for this, if precision is very important. Also <a href="https://stackoverflow.com/a/7091965/1044856"><code>@Naveens post</code></a>, is probably the most accurate, as it doesn't rely on the time of day.
<hr />

blocks|key|4892438|text|我在这里测试的所有答案(大约一半)都认为2000-02-29到2001-02-28是零年，因为2000-02-29到2001-03-01是1年零1天。这里有一个getYearDiff函数可以解决这个问题。它只适用于d0+<+d1|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|4892439|function+getYearDiff(d0,+d1)+{

++++d1+=+d1+%7C%7C+new+Date();

++++var+m+=+d0.getMonth();
++++var+years+=+d1.getFullYear()+-+d0.getFullYear();

++++d0.setFullYear(d0.getFullYear()+%2B+years);

++++if+(d0.getMonth()+!=+m)+d0.setDate(0);

++++return+d0+>+d1?+--years+:+years;
}|code-block|syntax|javascript|4892440|entityMap^0|2Z|7|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@$9|N|A|O|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|P|8|@]|D|@]|E|$I|J]]|$1|K|3|-4|5|6|7|Q|8|@]|D|@]|E|$]]]|L|$]]

All the answers I tested here (about half) think 2000-02-29 to 2001-02-28 is zero years, when it most likely should be 1 since 2000-02-29 to 2001-03-01 is 1 year and 1 day. Here is a getYearDiff function that fixes that. It only works where <code>d0 &lt; d1</code>:

<pre><code>function getYearDiff(d0, d1) {

 d1 = d1 || new Date();

 var m = d0.getMonth();
 var years = d1.getFullYear() - d0.getFullYear();

 d0.setFullYear(d0.getFullYear() + years);

 if (d0.getMonth() != m) d0.setDate(0);

 return d0 &gt; d1? --years : years;
}
</code></pre>

blocks|key|2002626|text|还有另一种解决方案：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2002627|/**
+*+Calculate+age+by+birth+date.
+*
+*+@param+int+birthYear+Year+as+YYYY.
+*+@param+int+birthMonth+Month+as+number+from+1+to+12.
+*+@param+int+birthDay+Day+as+number+from+1+to+31.
+*+@return+int
+*/
function+getAge(birthYear,+birthMonth,+birthDay)+{
++var+today+=+new+Date();
++var+birthDate+=+new+Date(birthYear,+birthMonth-1,+birthDay);
++var+age+=+today.getFullYear()+-+birthDate.getFullYear();
++var+m+=+today.getMonth()+-+birthDate.getMonth();
++if+(m+<+0+%7C%7C+(m+===+0+&&+today.getDate()+<+birthDate.getDate()))+{
++++age--;
++}
++return+age;
}|code-block|syntax|javascript|2002628|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Yet another solution:

<pre><code>/**
 * Calculate age by birth date.
 *
 * @param int birthYear Year as YYYY.
 * @param int birthMonth Month as number from 1 to 12.
 * @param int birthDay Day as number from 1 to 31.
 * @return int
 */
function getAge(birthYear, birthMonth, birthDay) {
 var today = new Date();
 var birthDate = new Date(birthYear, birthMonth-1, birthDay);
 var age = today.getFullYear() - birthDate.getFullYear();
 var m = today.getMonth() - birthDate.getMonth();
 if (m &lt; 0 || (m === 0 &amp;&amp; today.getDate() &lt; birthDate.getDate())) {
 age--;
 }
 return age;
}
</code></pre>

blocks|key|2002638|text|使用momentjs：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2002639|/*+The+difference,+in+years,+between+NOW+and+2012-05-07+*/
moment().diff(moment('20120507',+'YYYYMMDD'),+'years')|code-block|syntax|javascript|2002640|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

With momentjs:

<pre><code>/* The difference, in years, between NOW and 2012-05-07 */
moment().diff(moment('20120507', 'YYYYMMDD'), 'years')
</code></pre>

blocks|key|1259640|text|通过momentjs+"fromNow“方法，您可以处理格式化的日期，例如:+03/15/1968|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1259641|var+dob+=+document.getElementByID("dob");+var+age+=+moment(dob.value).fromNow(true).replace("+years",+"");|style|CODE|1259642|//fromNow(true)+=>+suffix+"ago"+is+not+displayed+//but+we+still+have+to+get+rid+of+"years";|1259643|作为原型版本|1259644|String.prototype.getAge+=+function()+{
return+moment(this.valueOf()).fromNow(true).replace("+years",+"");|code-block|syntax|javascript|1259645|}|1259646|entityMap|0|LINK|mutability|MUTABLE|url|http://momentjs.com/^0|2|8|0|0|0|2Y|0|0|2J|0|0|0|0^^$0|@$1|2|3|4|5|6|7|10|8|@]|9|@$A|11|B|12|1|13]]|C|$]]|$1|D|3|E|5|6|7|14|8|@$A|15|B|16|F|G]]|9|@]|C|$]]|$1|H|3|I|5|6|7|17|8|@$A|18|B|19|F|G]]|9|@]|C|$]]|$1|J|3|K|5|6|7|1A|8|@]|9|@]|C|$]]|$1|L|3|M|5|N|7|1B|8|@]|9|@]|C|$O|P]]|$1|Q|3|R|5|6|7|1C|8|@]|9|@]|C|$]]|$1|S|3|-4|5|6|7|1D|8|@]|9|@]|C|$]]]|T|$U|$5|V|W|X|C|$Y|Z]]]]

With <a href="http://momentjs.com/" rel="nofollow">momentjs</a> "fromNow" method, 
This allows you to work with formatted date, ie: 03/15/1968

<code>var dob = document.getElementByID("dob");
var age = moment(dob.value).fromNow(true).replace(" years", "");
</code>

<code>//fromNow(true) =&gt; suffix "ago" is not displayed
//but we still have to get rid of "years";
</code>

As a prototype version

<pre><code>String.prototype.getAge = function() {
return moment(this.valueOf()).fromNow(true).replace(" years", "");
</code></pre>

}

blocks|key|1259648|text|试试这个：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1259649|$('#Datepicker').change(function(){

var+$bef+=+$('#Datepicker').val();
var+$today+=+new+Date();
var+$before+=+new+Date($bef);
var+$befores+=+$before.getFullYear();
var+$todays+=+$today.getFullYear();
var+$bmonth+=+$before.getMonth();
var+$tmonth+=+$today.getMonth();
var+$bday+=+$before.getDate();
var+$tday+=+$today.getDate();

if+($bmonth>$tmonth)
{$('#age').val($todays-$befores);}

if+($bmonth==$tmonth)
{+++
if+($tday+>+$bday)+{$('#age').val($todays-$befores-1);}
else+if+($tday+<=+$bday)+{$('#age').val($todays-$befores);}
}
else+if+($bmonth<$tmonth)
{+$('#age').val($todays-$befores-1);}+
})|code-block|syntax|javascript|1259650|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Try this:

<pre><code>$('#Datepicker').change(function(){

var $bef = $('#Datepicker').val();
var $today = new Date();
var $before = new Date($bef);
var $befores = $before.getFullYear();
var $todays = $today.getFullYear();
var $bmonth = $before.getMonth();
var $tmonth = $today.getMonth();
var $bday = $before.getDate();
var $tday = $today.getDate();

if ($bmonth&gt;$tmonth)
{$('#age').val($todays-$befores);}

if ($bmonth==$tmonth)
{ 
if ($tday &gt; $bday) {$('#age').val($todays-$befores-1);}
else if ($tday &lt;= $bday) {$('#age').val($todays-$befores);}
}
else if ($bmonth&lt;$tmonth)
{ $('#age').val($todays-$befores-1);} 
})
</code></pre>

blocks|key|1257253|text|我使用这种方法使用逻辑而不是数学。它既精确又快速。参数是人的生日的年份、月份和日期。它返回一个整数形式的人的年龄。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1257254|function+calculateAge(year,+month,+day)+{
++++++++var+currentDate+=+new+Date();
++++++++var+currentYear+=+currentDate.getFullYear();
++++++++var+currentMonth+=+currentDate.getUTCMonth()+%2B+1;
++++++++var+currentDay+=+currentDate.getUTCDate();
++++++++//+You+need+to+treat+the+cases+where+the+year,+month+or+day+hasn't+arrived+yet.
++++++++var+age+=+currentYear+-+year;
++++++++if+(currentMonth+>+month)+{
++++++++++++return+age;
++++++++}+else+{
++++++++++++if+(currentDay+>=+day)+{
++++++++++++++++return+age;
++++++++++++}+else+{
++++++++++++++++age--;
++++++++++++++++return+age;
++++++++++++}
++++++++}
++++}|code-block|syntax|javascript|1257255|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

I used this approach using logic instead of math.
It's precise and quick.
The parameters are the year, month and day of the person's birthday.
It returns the person's age as an integer.

<pre><code>function calculateAge(year, month, day) {
 var currentDate = new Date();
 var currentYear = currentDate.getFullYear();
 var currentMonth = currentDate.getUTCMonth() + 1;
 var currentDay = currentDate.getUTCDate();
 // You need to treat the cases where the year, month or day hasn't arrived yet.
 var age = currentYear - year;
 if (currentMonth &gt; month) {
 return age;
 } else {
 if (currentDay &gt;= day) {
 return age;
 } else {
 age--;
 return age;
 }
 }
 }
</code></pre>

blocks|key|1257264|text|我有一个很好的答案，尽管这不是我的代码。不幸的是，我忘记了原来的帖子。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1257265|function+calculateAge(y,+m,+d)+{
++++var+_birth+=+parseInt(""+%2B+y+%2B+affixZero(m)+%2B+affixZero(d));
++++var++today+=+new+Date();
++++var+_today+=+parseInt(""+%2B+today.getFullYear()+%2B+affixZero(today.getMonth()+%2B+1)+%2B+affixZero(today.getDate()));
++++return+parseInt((_today+-+_birth)+/+10000);
}
function+affixZero(int)+{
++++if+(int+<+10)+int+=+"0"+%2B+int;
++++return+""+%2B+int;
}
var+age+=+calculateAge(1980,+4,+22);
alert(age);|code-block|syntax|javascript|1257266|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

I have a pretty answer although it's not my code. Unfortunately I forgot the original post. 

<pre><code>function calculateAge(y, m, d) {
 var _birth = parseInt("" + y + affixZero(m) + affixZero(d));
 var today = new Date();
 var _today = parseInt("" + today.getFullYear() + affixZero(today.getMonth() + 1) + affixZero(today.getDate()));
 return parseInt((_today - _birth) / 10000);
}
function affixZero(int) {
 if (int &lt; 10) int = "0" + int;
 return "" + int;
}
var age = calculateAge(1980, 4, 22);
alert(age);
</code></pre>

blocks|key|1257281|text|查看此示例，您可以从此处获取完整的年、月、日信息|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1257282|function+getAge(dateString)+{
++++var+today+=+new+Date();
++++var+birthDate+=+new+Date(dateString);
++++var+age+=+today.getFullYear()+-+birthDate.getFullYear();
++++var+m+=+today.getMonth()+-+birthDate.getMonth();
++++var+da+=+today.getDate()+-+birthDate.getDate();
++++if+(m+<+0+%7C%7C+(m+===+0+&&+today.getDate()+<+birthDate.getDate()))+{
++++++++age--;
++++}
++++if(m<0){
++++++++m+%2B=12;
++++}
++++if(da<0){
++++++++da+%2B=30;
++++}
++++return+age%2B"+years+"%2B+Math.abs(m)+%2B+"months"%2B+Math.abs(da)+%2B+"+days";
}
alert('age:+'+%2B+getAge("1987/08/31"));++++
[http://jsfiddle.net/tapos00/2g70ue5y/][1]|code-block|syntax|javascript|1257283|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

see this example you get full year month day information from here 

<pre><code>function getAge(dateString) {
 var today = new Date();
 var birthDate = new Date(dateString);
 var age = today.getFullYear() - birthDate.getFullYear();
 var m = today.getMonth() - birthDate.getMonth();
 var da = today.getDate() - birthDate.getDate();
 if (m &lt; 0 || (m === 0 &amp;&amp; today.getDate() &lt; birthDate.getDate())) {
 age--;
 }
 if(m&lt;0){
 m +=12;
 }
 if(da&lt;0){
 da +=30;
 }
 return age+" years "+ Math.abs(m) + "months"+ Math.abs(da) + " days";
}
alert('age: ' + getAge("1987/08/31")); 
[http://jsfiddle.net/tapos00/2g70ue5y/][1]
</code></pre>

blocks|key|2002725|text|如果您需要以月为单位的年龄(天数是近似值)：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2002726|birthDay=28;
birthMonth=7;
birthYear=1974;

var++today+=+new+Date();
currentDay=today.getUTCDate();
currentMonth=today.getUTCMonth()+%2B+1;
currentYear=today.getFullYear();

//calculate+the+age+in+months:
Age+=+(currentYear-birthYear)*12+%2B+(currentMonth-birthMonth)+%2B+(currentDay-birthDay)/30;|code-block|syntax|javascript|2002727|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

If you need the age in months (days are approximation):

<pre><code>birthDay=28;
birthMonth=7;
birthYear=1974;

var today = new Date();
currentDay=today.getUTCDate();
currentMonth=today.getUTCMonth() + 1;
currentYear=today.getFullYear();

//calculate the age in months:
Age = (currentYear-birthYear)*12 + (currentMonth-birthMonth) + (currentDay-birthDay)/30;
</code></pre>

blocks|key|4892658|text|$("#birthday").change(function+(){


var+val=this.value;

var+current_year=new+Date().getFullYear();
if(val!=null){
++++var+Split+=+val.split("-");
++++var+birth_year=parseInt(Split[2]);

++++if(parseInt(current_year)-parseInt(birth_year)<parseInt(18)){

++$("#maritial_status").attr('disabled',+'disabled');
++++++++var+val2=+document.getElementById("maritial_status");
++++++++val2.value+=+"Not+Married";
++++++++$("#anniversary").attr('disabled',+'disabled');
++++++++var+val1=+document.getElementById("anniversary");
++++++++val1.value+=+"NA";

++++}else{
++++++++$("#maritial_status").attr('disabled',+false);
++++++++$("#anniversary").attr('disabled',+false);

++++}
}
});|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|4892659|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>$("#birthday").change(function (){


var val=this.value;

var current_year=new Date().getFullYear();
if(val!=null){
 var Split = val.split("-");
 var birth_year=parseInt(Split[2]);

 if(parseInt(current_year)-parseInt(birth_year)&lt;parseInt(18)){

 $("#maritial_status").attr('disabled', 'disabled');
 var val2= document.getElementById("maritial_status");
 val2.value = "Not Married";
 $("#anniversary").attr('disabled', 'disabled');
 var val1= document.getElementById("anniversary");
 val1.value = "NA";

 }else{
 $("#maritial_status").attr('disabled', false);
 $("#anniversary").attr('disabled', false);

 }
}
});
</code></pre>

blocks|key|1259728|text|function+change(){
++++setTimeout(function(){
++++++++var+dateObj++=++++++new+Date();
++++++++++++++++++++var+month++++=++++++dateObj.getUTCMonth()+%2B+1;+//months+from+1-12
++++++++++++++++++++var+day++++++=++++++dateObj.getUTCDate();
++++++++++++++++++++var+year+++++=++++++dateObj.getUTCFullYear();++
++++++++++++++++++++var+newdate++=++++++year+%2B+"/"+%2B+month+%2B+"/"+%2B+day;
++++++++++++++++++++var+entered_birthdate++++++++=+++document.getElementById('birth_dates').value;
++++++++++++++++++++var+birthdate++++++++++++++++=+++new+Date(entered_birthdate);
++++++++++++++++++++var+birth_year+++++++++++++++=+++birthdate.getUTCFullYear();
++++++++++++++++++++var+birth_month++++++++++++++=+++birthdate.getUTCMonth()+%2B+1;
++++++++++++++++++++var+birth_date+++++++++++++++=+++birthdate.getUTCDate();
++++++++++++++++++++var+age_year++++++++++++++++=++++(year-birth_year);
++++++++++++++++++++var+age_month+++++++++++++++=++++(month-birth_month);
++++++++++++++++++++var+age_date++++++++++++++++=++++((day-birth_date)+<+0)?(31%2B(day-birth_date)):(day-birth_date);
++++++++++++++++++++var+test++++++++++++++++++++=++++(birth_year>year)?true:((age_year===0)?((month<birth_month)?true:((month===birth_month)?(day+<+birth_date):false)):false)+;
+++++++++++++++++++if+(test+===+true+%7C%7C+(document.getElementById("birth_dates").value===+"")){
++++++++++++++++++++++++document.getElementById("ages").innerHTML+=+"";
++++++++++++++++++++}++++++++++++++++++++else{
++++++++++++++++++++++++var+age+++++++++++++++++++++=++++(age_year+>+1)?age_year:(+++((age_year===+1+)&&(age_month+>=+0))?age_year:((age_month+<+0)?(age_month%2B12):((age_month+>+1)?age_month:++++++(++((age_month===1)+&&+(day>birth_date)+)+?+age_month:age_date)++++++++++)++++));+
++++++++++++++++++++++++var+ages++++++++++++++++++++=++++((age===age_date)&&(age!==age_month)&&(age!==age_year))?(age_date%2B"days"):((((age===age_month%2B12)%7C%7C(age===age_month)&&(age!==age_year))?(age%2B"months"):age_year%2B"years"));
++++++++++++++++++++++++document.getElementById("ages").innerHTML+=+ages;
++++++++++++++++++}
++++++++++++++++},+30);

};|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1259729|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>function change(){
 setTimeout(function(){
 var dateObj = new Date();
 var month = dateObj.getUTCMonth() + 1; //months from 1-12
 var day = dateObj.getUTCDate();
 var year = dateObj.getUTCFullYear(); 
 var newdate = year + "/" + month + "/" + day;
 var entered_birthdate = document.getElementById('birth_dates').value;
 var birthdate = new Date(entered_birthdate);
 var birth_year = birthdate.getUTCFullYear();
 var birth_month = birthdate.getUTCMonth() + 1;
 var birth_date = birthdate.getUTCDate();
 var age_year = (year-birth_year);
 var age_month = (month-birth_month);
 var age_date = ((day-birth_date) &lt; 0)?(31+(day-birth_date)):(day-birth_date);
 var test = (birth_year&gt;year)?true:((age_year===0)?((month&lt;birth_month)?true:((month===birth_month)?(day &lt; birth_date):false)):false) ;
 if (test === true || (document.getElementById("birth_dates").value=== "")){
 document.getElementById("ages").innerHTML = "";
 } else{
 var age = (age_year &gt; 1)?age_year:( ((age_year=== 1 )&amp;&amp;(age_month &gt;= 0))?age_year:((age_month &lt; 0)?(age_month+12):((age_month &gt; 1)?age_month: ( ((age_month===1) &amp;&amp; (day&gt;birth_date) ) ? age_month:age_date) ) )); 
 var ages = ((age===age_date)&amp;&amp;(age!==age_month)&amp;&amp;(age!==age_year))?(age_date+"days"):((((age===age_month+12)||(age===age_month)&amp;&amp;(age!==age_year))?(age+"months"):age_year+"years"));
 document.getElementById("ages").innerHTML = ages;
 }
 }, 30);

};
</code></pre>

blocks|key|3481156|text|从日期选择器计算年龄|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3481157|+++++++++$('#ContentPlaceHolder1_dob').on('changeDate',+function+(ev)+{
++++++++++++$(this).datepicker('hide');

++++++++++++//alert($(this).val());
++++++++++++var+date+=+formatDate($(this).val());+//+('2010/01/18')+to+("1990/4/16"))
++++++++++++var+age+=+getAge(date);

++++++++++++$("#ContentPlaceHolder1_age").val(age);
++++++++});


++++function+formatDate(input)+{
++++++++var+datePart+=+input.match(/\d%2B/g),
++++++++year+=+datePart[0],+//+get+only+two+digits
++++++++month+=+datePart[1],+day+=+datePart[2];
++++++++return+day+%2B+'/'+%2B+month+%2B+'/'+%2B+year;
++++}

++++//+alert(formatDate('2010/01/18'));


++++function+getAge(dateString)+{
++++++++var+today+=+new+Date();
++++++++var+birthDate+=+new+Date(dateString);
++++++++var+age+=+today.getFullYear()+-+birthDate.getFullYear();
++++++++var+m+=+today.getMonth()+-+birthDate.getMonth();
++++++++if+(m+<+0+%7C%7C+(m+===+0+&&+today.getDate()+<+birthDate.getDate()))+{
++++++++++++age--;
++++++++}
++++++++return+age;
++++}|code-block|syntax|javascript|3481158|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Calculate age from date picker

<pre><code> $('#ContentPlaceHolder1_dob').on('changeDate', function (ev) {
 $(this).datepicker('hide');

 //alert($(this).val());
 var date = formatDate($(this).val()); // ('2010/01/18') to ("1990/4/16"))
 var age = getAge(date);

 $("#ContentPlaceHolder1_age").val(age);
 });


 function formatDate(input) {
 var datePart = input.match(/\d+/g),
 year = datePart[0], // get only two digits
 month = datePart[1], day = datePart[2];
 return day + '/' + month + '/' + year;
 }

 // alert(formatDate('2010/01/18'));


 function getAge(dateString) {
 var today = new Date();
 var birthDate = new Date(dateString);
 var age = today.getFullYear() - birthDate.getFullYear();
 var m = today.getMonth() - birthDate.getMonth();
 if (m &lt; 0 || (m === 0 &amp;&amp; today.getDate() &lt; birthDate.getDate())) {
 age--;
 }
 return age;
 }
</code></pre>

blocks|key|3481191|text|我采用了纳维恩和原始OP的帖子，最终得到了一个可重用的方法存根，它接受字符串和/或JS+Date对象。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3481192|我将其命名为gregorianAge()，因为这个计算给出了我们使用公历表示年龄的确切方式。即，如果月份和日期在出生年份的月份和日期之前，则不计算结束年。|offset|length|style|CODE|3481193|​|3481194|/**
+*+Calculates+human+age+in+years+given+a+birth+day.+Optionally+ageAtDate
+*+can+be+provided+to+calculate+age+at+a+specific+date
+*
+*+@param+string%7CDate+Object+birthDate
+*+@param+string%7CDate+Object+ageAtDate+optional
+*+@returns+integer+Age+between+birthday+and+a+given+date+or+today
+*/
function+gregorianAge(birthDate,+ageAtDate)+{
++//+convert+birthDate+to+date+object+if+already+not
++if+(Object.prototype.toString.call(birthDate)+!==+'[object+Date]')
++++birthDate+=+new+Date(birthDate);

++//+use+today's+date+if+ageAtDate+is+not+provided
++if+(typeof+ageAtDate+==+"undefined")
++++ageAtDate+=+new+Date();

++//+convert+ageAtDate+to+date+object+if+already+not
++else+if+(Object.prototype.toString.call(ageAtDate)+!==+'[object+Date]')
++++ageAtDate+=+new+Date(ageAtDate);

++//+if+conversion+to+date+object+fails+return+null
++if+(ageAtDate+==+null+%7C%7C+birthDate+==+null)
++++return+null;


++var+_m+=+ageAtDate.getMonth()+-+birthDate.getMonth();

++//+answer:+ageAt+year+minus+birth+year+less+one+(1)+if+month+and+day+of
++//+ageAt+year+is+before+month+and+day+of+birth+year
++return+(ageAtDate.getFullYear())+-+birthDate.getFullYear()+
++-+((_m+<+0+%7C%7C+(_m+===+0+&&+ageAtDate.getDate()+<+birthDate.getDate()))+?+1+:+0)
}

//+Below+is+for+the+attached+snippet

function+showAge()+{
++$('#age').text(gregorianAge($('#dob').val()))
}

$(function()+{
++$(".datepicker").datepicker();
++showAge();
});|code-block|syntax|javascript|3481195|<link+rel="stylesheet"+href="//code.jquery.com/ui/1.11.4/themes/smoothness/jquery-ui.css">
<script+src="//code.jquery.com/jquery-1.10.2.js"></script>
<script+src="//code.jquery.com/ui/1.11.4/jquery-ui.js"></script>

DOB:
<input+name="dob"+value="12/31/1970"+id="dob"+class="datepicker"+onChange="showAge()"+/>+AGE:+<span+id="age">|3481196|3481197|entityMap^0|0|6|E|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|T|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|U|8|@$D|V|E|W|F|G]]|9|@]|A|$]]|$1|H|3|I|5|6|7|X|8|@]|9|@]|A|$]]|$1|J|3|K|5|L|7|Y|8|@]|9|@]|A|$M|N]]|$1|O|3|P|5|L|7|Z|8|@]|9|@]|A|$M|N]]|$1|Q|3|I|5|6|7|10|8|@]|9|@]|A|$]]|$1|R|3|-4|5|6|7|11|8|@]|9|@]|A|$]]]|S|$]]

Adopting from naveen's and original OP's posts I ended up with a reusable method stub that accepts both strings and / or JS Date objects.

I named it <code>gregorianAge()</code> because this calculation gives exactly how we denote age using Gregorian calendar. i.e. Not counting the end year if month and day is before the month and day of the birth year.

<div class="snippet" data-lang="js" data-hide="false">
<div class="snippet-code">
<pre class="snippet-code-js lang-js prettyprint-override"><code>/**
 * Calculates human age in years given a birth day. Optionally ageAtDate
 * can be provided to calculate age at a specific date
 *
 * @param string|Date Object birthDate
 * @param string|Date Object ageAtDate optional
 * @returns integer Age between birthday and a given date or today
 */
function gregorianAge(birthDate, ageAtDate) {
 // convert birthDate to date object if already not
 if (Object.prototype.toString.call(birthDate) !== '[object Date]')
 birthDate = new Date(birthDate);

 // use today's date if ageAtDate is not provided
 if (typeof ageAtDate == "undefined")
 ageAtDate = new Date();

 // convert ageAtDate to date object if already not
 else if (Object.prototype.toString.call(ageAtDate) !== '[object Date]')
 ageAtDate = new Date(ageAtDate);

 // if conversion to date object fails return null
 if (ageAtDate == null || birthDate == null)
 return null;


 var _m = ageAtDate.getMonth() - birthDate.getMonth();

 // answer: ageAt year minus birth year less one (1) if month and day of
 // ageAt year is before month and day of birth year
 return (ageAtDate.getFullYear()) - birthDate.getFullYear() 
 - ((_m &lt; 0 || (_m === 0 &amp;&amp; ageAtDate.getDate() &lt; birthDate.getDate())) ? 1 : 0)
}

// Below is for the attached snippet

function showAge() {
 $('#age').text(gregorianAge($('#dob').val()))
}

$(function() {
 $(".datepicker").datepicker();
 showAge();
});</code></pre>
<pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;link rel="stylesheet" href="//code.jquery.com/ui/1.11.4/themes/smoothness/jquery-ui.css"&gt;
&lt;script src="//code.jquery.com/jquery-1.10.2.js"&gt;&lt;/script&gt;
&lt;script src="//code.jquery.com/ui/1.11.4/jquery-ui.js"&gt;&lt;/script&gt;

DOB:
&lt;input name="dob" value="12/31/1970" id="dob" class="datepicker" onChange="showAge()" /&gt; AGE: &lt;span id="age"&gt;&lt;span&gt;</code></pre>
</div>
</div>

blocks|key|2002875|text|另外两个选项：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|2002876|//+Int+Age+to+Date+as+string+YYY-mm-dd
function+age_to_date(age)
{
++++try+{
++++++++var+d+=+new+Date();
++++++++var+new_d+=+'';
++++++++d.setFullYear(d.getFullYear()+-+Math.abs(age));
++++++++new_d+=+d.getFullYear()+%2B+'-'+%2B+d.getMonth()+%2B+'-'+%2B+d.getDate();

++++++++return+new_d;
++++}+catch(err)+{
++++++++console.log(err.message);
++++}
}
//+Date+string+(YYY-mm-dd)+to+Int+age+(years+old)
function+date_to_age(date)
{
++++try+{
++++++++var+today+=+new+Date();
++++++++var+d+=+new+Date(date);

++++++++var+year+=+today.getFullYear()+-+d.getFullYear();
++++++++var+month+=+today.getMonth()+-+d.getMonth();
++++++++var+day+=+today.getDate()+-+d.getDate();
++++++++var+carry+=+0;

++++++++if+(year+<+0)
++++++++++++return+0;
++++++++if+(month+<=+0+&&+day+<=+0)
++++++++++++carry+-=+1;

++++++++var+age+=+parseInt(year);
++++++++age+%2B=+carry;

++++++++return+Math.abs(age);
++++}+catch(err)+{
++++++++console.log(err.message);
++++}
}|code-block|syntax|javascript|2002877|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Two more options:

<pre><code>// Int Age to Date as string YYY-mm-dd
function age_to_date(age)
{
 try {
 var d = new Date();
 var new_d = '';
 d.setFullYear(d.getFullYear() - Math.abs(age));
 new_d = d.getFullYear() + '-' + d.getMonth() + '-' + d.getDate();

 return new_d;
 } catch(err) {
 console.log(err.message);
 }
}
// Date string (YYY-mm-dd) to Int age (years old)
function date_to_age(date)
{
 try {
 var today = new Date();
 var d = new Date(date);

 var year = today.getFullYear() - d.getFullYear();
 var month = today.getMonth() - d.getMonth();
 var day = today.getDate() - d.getDate();
 var carry = 0;

 if (year &lt; 0)
 return 0;
 if (month &lt;= 0 &amp;&amp; day &lt;= 0)
 carry -= 1;

 var age = parseInt(year);
 age += carry;

 return Math.abs(age);
 } catch(err) {
 console.log(err.message);
 }
}
</code></pre>

blocks|key|1257472|text|我对之前的一个答案做了一些更新。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1257473|var+calculateAge+=+function(dob)+{
++++var+days+=+function(date)+{
++++++++++++return+31*date.getMonth()+%2B+date.getDate();
++++++++},
++++++++d+=+new+Date(dob*1000),
++++++++now+=+new+Date();

++++return+now.getFullYear()+-+d.getFullYear()+-+(+measureDays(now)+<+measureDays(d));
}|code-block|syntax|javascript|1257474|我希望这会有帮助:D|1257475|entityMap^0|0|0|0^^$0|@$1|2|3|4|5|6|7|K|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|L|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|M|8|@]|9|@]|A|$]]|$1|I|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|J|$]]

I've did some updated to one previous answer.

<pre><code>var calculateAge = function(dob) {
 var days = function(date) {
 return 31*date.getMonth() + date.getDate();
 },
 d = new Date(dob*1000),
 now = new Date();

 return now.getFullYear() - d.getFullYear() - ( measureDays(now) &lt; measureDays(d));
}
</code></pre>

I hope that helps :D

blocks|key|4892956|text|这里有一个计算年龄的简单方法：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4892957|//dob+date+dd/mm/yy+
var+d+=+01/01/1990


//today
//date+today+string+format+
var+today+=+new+Date();+//+i.e+wed+04+may+2016+15:12:09+GMT
//todays+year
var+todayYear+=+today.getFullYear();
//+today+month
var+todayMonth+=+today.getMonth();
//today+date
var+todayDate+=+today.getDate();

//dob
//dob+parsed+as+date+format+++
var+dob+=+new+Date(d);
//+dob+year
var+dobYear+=+dob.getFullYear();
//+dob+month
var+dobMonth+=+dob.getMonth();
//dob+date
var+dobDate+=+dob.getDate();

var+yearsDiff+=+todayYear+-+dobYear+;
var+age;

if+(+todayMonth+<+dobMonth+)+
+{+
++age+=+yearsDiff+-+1;+
+}
else+if+(+todayMonth+>+dobMonth+)+
+{
++age+=+yearsDiff+;+
+}

else+//if+today+month+=+dob+month
+{+if+(+todayDate+<+dobDate+)+
++{
+++age+=+yearsDiff+-+1;
++}
++++else+
++++{
+++++age+=+yearsDiff;
++++}
+}|code-block|syntax|javascript|4892958|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

here is a simple way of calculating age: 

<pre><code>//dob date dd/mm/yy 
var d = 01/01/1990


//today
//date today string format 
var today = new Date(); // i.e wed 04 may 2016 15:12:09 GMT
//todays year
var todayYear = today.getFullYear();
// today month
var todayMonth = today.getMonth();
//today date
var todayDate = today.getDate();

//dob
//dob parsed as date format 
var dob = new Date(d);
// dob year
var dobYear = dob.getFullYear();
// dob month
var dobMonth = dob.getMonth();
//dob date
var dobDate = dob.getDate();

var yearsDiff = todayYear - dobYear ;
var age;

if ( todayMonth &lt; dobMonth ) 
 { 
 age = yearsDiff - 1; 
 }
else if ( todayMonth &gt; dobMonth ) 
 {
 age = yearsDiff ; 
 }

else //if today month = dob month
 { if ( todayDate &lt; dobDate ) 
 {
 age = yearsDiff - 1;
 }
 else 
 {
 age = yearsDiff;
 }
 }
</code></pre>

blocks|key|4892973|text|我认为这可能很简单：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4892974|function+age(dateString){
++++let+birth+=+new+Date(dateString);
++++let+now+=+new+Date();
++++let+beforeBirth+=+((()+=>+{birth.setDate(now.getDate());birth.setMonth(now.getMonth());+return+birth.getTime()})()+<+birth.getTime())+?+0+:+1;
++++return+now.getFullYear()+-+birth.getFullYear()+-+beforeBirth;
}

age('09/20/1981');
//35|code-block|syntax|javascript|4892975|也可以使用时间戳。|4892976|age(403501000000)
//34|4892977|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|N|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|O|8|@]|9|@]|A|$]]|$1|I|3|J|5|D|7|P|8|@]|9|@]|A|$E|F]]|$1|K|3|-4|5|6|7|Q|8|@]|9|@]|A|$]]]|L|$]]

I think that could be simply like that:

<pre><code>function age(dateString){
 let birth = new Date(dateString);
 let now = new Date();
 let beforeBirth = ((() =&gt; {birth.setDate(now.getDate());birth.setMonth(now.getMonth()); return birth.getTime()})() &lt; birth.getTime()) ? 0 : 1;
 return now.getFullYear() - birth.getFullYear() - beforeBirth;
}

age('09/20/1981');
//35
</code></pre>

Works also with a timestamp

<pre><code>age(403501000000)
//34
</code></pre>

blocks|key|4893012|text|Get+the+age+(years,+months+and+days)+from+the+date+of+birth+with+javascript|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|4893013|函数calcularEdad+(年、月、日)|4893014|function+calcularEdad(fecha)+{
++++++++//+Si+la+fecha+es+correcta,+calculamos+la+edad

++++++++if+(typeof+fecha+!=+"string"+&&+fecha+&&+esNumero(fecha.getTime()))+{
++++++++++++fecha+=+formatDate(fecha,+"yyyy-MM-dd");
++++++++}

++++++++var+values+=+fecha.split("-");
++++++++var+dia+=+values[2];
++++++++var+mes+=+values[1];
++++++++var+ano+=+values[0];

++++++++//+cogemos+los+valores+actuales
++++++++var+fecha_hoy+=+new+Date();
++++++++var+ahora_ano+=+fecha_hoy.getYear();
++++++++var+ahora_mes+=+fecha_hoy.getMonth()+%2B+1;
++++++++var+ahora_dia+=+fecha_hoy.getDate();

++++++++//+realizamos+el+calculo
++++++++var+edad+=+(ahora_ano+%2B+1900)+-+ano;
++++++++if+(ahora_mes+<+mes)+{
++++++++++++edad--;
++++++++}
++++++++if+((mes+==+ahora_mes)+&&+(ahora_dia+<+dia))+{
++++++++++++edad--;
++++++++}
++++++++if+(edad+>+1900)+{
++++++++++++edad+-=+1900;
++++++++}

++++++++//+calculamos+los+meses
++++++++var+meses+=+0;

++++++++if+(ahora_mes+>+mes+&&+dia+>+ahora_dia)
++++++++++++meses+=+ahora_mes+-+mes+-+1;
++++++++else+if+(ahora_mes+>+mes)
++++++++++++meses+=+ahora_mes+-+mes
++++++++if+(ahora_mes+<+mes+&&+dia+<+ahora_dia)
++++++++++++meses+=+12+-+(mes+-+ahora_mes);
++++++++else+if+(ahora_mes+<+mes)
++++++++++++meses+=+12+-+(mes+-+ahora_mes+%2B+1);
++++++++if+(ahora_mes+==+mes+&&+dia+>+ahora_dia)
++++++++++++meses+=+11;

++++++++//+calculamos+los+dias
++++++++var+dias+=+0;
++++++++if+(ahora_dia+>+dia)
++++++++++++dias+=+ahora_dia+-+dia;
++++++++if+(ahora_dia+<+dia)+{
++++++++++++ultimoDiaMes+=+new+Date(ahora_ano,+ahora_mes+-+1,+0);
++++++++++++dias+=+ultimoDiaMes.getDate()+-+(dia+-+ahora_dia);
++++++++}

++++++++return+edad+%2B+"+años,+"+%2B+meses+%2B+"+meses+y+"+%2B+dias+%2B+"+días";
++++}|code-block|syntax|javascript|4893015|函数esNumero|4893016|function+esNumero(strNumber)+{
++++if+(strNumber+==+null)+return+false;
++++if+(strNumber+==+undefined)+return+false;
++++if+(typeof+strNumber+===+"number"+&&+!isNaN(strNumber))+return+true;
++++if+(strNumber+==+"")+return+false;
++++if+(strNumber+===+"")+return+false;
++++var+psInt,+psFloat;
++++psInt+=+parseInt(strNumber);
++++psFloat+=+parseFloat(strNumber);
++++return+!isNaN(strNumber)+&&+!isNaN(psFloat);
}|4893017|entityMap|0|LINK|mutability|MUTABLE|url|http://aandresdev.blogspot.pe/2017/01/obtener-la-edad-anos-meses-y-dias.html^0|0|23|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@$A|X|B|Y|1|Z]]|C|$]]|$1|D|3|E|5|6|7|10|8|@]|9|@]|C|$]]|$1|F|3|G|5|H|7|11|8|@]|9|@]|C|$I|J]]|$1|K|3|L|5|6|7|12|8|@]|9|@]|C|$]]|$1|M|3|N|5|H|7|13|8|@]|9|@]|C|$I|J]]|$1|O|3|-4|5|6|7|14|8|@]|9|@]|C|$]]]|P|$Q|$5|R|S|T|C|$U|V]]]]

<a href="http://aandresdev.blogspot.pe/2017/01/obtener-la-edad-anos-meses-y-dias.html" rel="nofollow noreferrer">Get the age (years, months and days) from the date of birth with javascript</a>

Function calcularEdad (years, months and days)

<pre><code>function calcularEdad(fecha) {
 // Si la fecha es correcta, calculamos la edad

 if (typeof fecha != "string" &amp;&amp; fecha &amp;&amp; esNumero(fecha.getTime())) {
 fecha = formatDate(fecha, "yyyy-MM-dd");
 }

 var values = fecha.split("-");
 var dia = values[2];
 var mes = values[1];
 var ano = values[0];

 // cogemos los valores actuales
 var fecha_hoy = new Date();
 var ahora_ano = fecha_hoy.getYear();
 var ahora_mes = fecha_hoy.getMonth() + 1;
 var ahora_dia = fecha_hoy.getDate();

 // realizamos el calculo
 var edad = (ahora_ano + 1900) - ano;
 if (ahora_mes &lt; mes) {
 edad--;
 }
 if ((mes == ahora_mes) &amp;&amp; (ahora_dia &lt; dia)) {
 edad--;
 }
 if (edad &gt; 1900) {
 edad -= 1900;
 }

 // calculamos los meses
 var meses = 0;

 if (ahora_mes &gt; mes &amp;&amp; dia &gt; ahora_dia)
 meses = ahora_mes - mes - 1;
 else if (ahora_mes &gt; mes)
 meses = ahora_mes - mes
 if (ahora_mes &lt; mes &amp;&amp; dia &lt; ahora_dia)
 meses = 12 - (mes - ahora_mes);
 else if (ahora_mes &lt; mes)
 meses = 12 - (mes - ahora_mes + 1);
 if (ahora_mes == mes &amp;&amp; dia &gt; ahora_dia)
 meses = 11;

 // calculamos los dias
 var dias = 0;
 if (ahora_dia &gt; dia)
 dias = ahora_dia - dia;
 if (ahora_dia &lt; dia) {
 ultimoDiaMes = new Date(ahora_ano, ahora_mes - 1, 0);
 dias = ultimoDiaMes.getDate() - (dia - ahora_dia);
 }

 return edad + " años, " + meses + " meses y " + dias + " días";
 }
</code></pre>

Function esNumero

<pre><code>function esNumero(strNumber) {
 if (strNumber == null) return false;
 if (strNumber == undefined) return false;
 if (typeof strNumber === "number" &amp;&amp; !isNaN(strNumber)) return true;
 if (strNumber == "") return false;
 if (strNumber === "") return false;
 var psInt, psFloat;
 psInt = parseInt(strNumber);
 psFloat = parseFloat(strNumber);
 return !isNaN(strNumber) &amp;&amp; !isNaN(psFloat);
}
</code></pre>

blocks|key|3481454|text|另一种可能的解决方案是moment.js|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|3481455|var+moment+=+require('moment');
var+startDate+=+new+Date();
var+endDate+=+new+Date();
endDate.setDate(endDate.getFullYear()+%2B+5);+//+Add+5+years+to+second+date
console.log(moment.duration(endDate+-+startDate).years());+//+This+should+returns+5|code-block|syntax|javascript|3481456|entityMap|0|LINK|mutability|MUTABLE|url|http://momentjs.com/^0|B|9|0|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@$A|R|B|S|1|T]]|C|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|C|$G|H]]|$1|I|3|-4|5|6|7|V|8|@]|9|@]|C|$]]]|J|$K|$5|L|M|N|C|$O|P]]]]

One more possible solution with <a href="http://momentjs.com" rel="nofollow noreferrer">moment.js</a>:

<pre><code>var moment = require('moment');
var startDate = new Date();
var endDate = new Date();
endDate.setDate(endDate.getFullYear() + 5); // Add 5 years to second date
console.log(moment.duration(endDate - startDate).years()); // This should returns 5
</code></pre>

blocks|key|4893029|text|var+now+=+DateTime.Now;
var+age+=+DateTime.Now.Year+-+dob.Year;
if+(now.Month+<+dob.Month+%7C%7C+now.Month+==+dob.Month+&&+now.Day+<+dob.Day)+age--;|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|4893030|unstyled|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|G|8|@]|9|@]|A|$B|C]]|$1|D|3|-4|5|E|7|H|8|@]|9|@]|A|$]]]|F|$]]

<pre><code>var now = DateTime.Now;
var age = DateTime.Now.Year - dob.Year;
if (now.Month &lt; dob.Month || now.Month == dob.Month &amp;&amp; now.Day &lt; dob.Day) age--;
</code></pre>

blocks|key|4893080|text|使用ES6:清理单行程序解决方案|type|unstyled|depth|inlineStyleRanges|offset|length|style|BOLD|entityRanges|data|4893081|const+getAge+=+birthDate+=>+Math.floor((new+Date()+-+new+Date(birthDate).getTime())+/+3.15576e%2B10)

//+today+is+2018-06-13
getAge('1994-06-14')+//+23
getAge('1994-06-13')+//+24|code-block|syntax|javascript|4893082|我使用的年份是365.25天(因为是闰年)，它们分别是3.15576e%2B10毫秒(365.25+*+24+*+60+*+60+*+1000)。|4893083|它有几个小时的余量，所以根据用例的不同，它可能不是最好的选择。|4893084|entityMap^0|8|8|0|0|0|1Z|0|0|V|0^^$0|@$1|2|3|4|5|6|7|Q|8|@$9|R|A|S|B|C]]|D|@]|E|$]]|$1|F|3|G|5|H|7|T|8|@]|D|@]|E|$I|J]]|$1|K|3|L|5|6|7|U|8|@$9|V|A|W|B|C]]|D|@]|E|$]]|$1|M|3|N|5|6|7|X|8|@$9|Y|A|Z|B|C]]|D|@]|E|$]]|$1|O|3|-4|5|6|7|10|8|@]|D|@]|E|$]]]|P|$]]

Clean one-liner solution using ES6:
<pre><code>const getAge = birthDate =&gt; Math.floor((new Date() - new Date(birthDate).getTime()) / 3.15576e+10)

// today is 2018-06-13
getAge('1994-06-14') // 23
getAge('1994-06-13') // 24
</code></pre>
I am using a year of 365.25 days (0.25 because of leap years) which are 3.15576e+10 milliseconds (365.25 * 24 * 60 * 60 * 1000) respectively.
It has a few hours margin so depending on the use case it may not be the best option.

blocks|key|3481525|text|很适合我，伙计们。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3481526|getAge(birthday)+{
++++const+millis+=+Date.now()+-+Date.parse(birthday);
++++return+new+Date(millis).getFullYear()+-+1970;
}|code-block|syntax|javascript|3481527|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Works perfect for me, guys.

<pre><code>getAge(birthday) {
 const millis = Date.now() - Date.parse(birthday);
 return new Date(millis).getFullYear() - 1970;
}
</code></pre>

blocks|key|4893136|text|在您的表单-中，您可以使用此选项进行年龄限制|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4893137|function+dobvalidator(birthDateString){
++++strs+=+birthDateString.split("-");
++++var+dd+=+strs[0];
++++var+mm+=+strs[1];
++++var+yy+=+strs[2];

++++var+d+=+new+Date();
++++var+ds+=+d.getDate();
++++var+ms+=+d.getMonth();
++++var+ys+=+d.getFullYear();
++++var+accepted_age+=+18;

++++var+days+=+((accepted_age+*+12)+*+30)+%2B+(ms+*+30)+%2B+ds;
++++var+age+=+(((ys+-+yy)+*+12)+*+30)+%2B+((12+-+mm)+*+30)+%2B+parseInt(30+-+dd);

++++if((days+-+age)+<=+'0'){
++++++++console.log((days+-+age));
++++++++alert('You+are+at-least+'+%2B+accepted_age);
++++}else{
++++++++console.log((days+-+age));
++++++++alert('You+are+not+at-least+'+%2B+accepted_age);
++++}
}|code-block|syntax|javascript|4893138|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

You may use this for age restriction in your form -

<pre><code>function dobvalidator(birthDateString){
 strs = birthDateString.split("-");
 var dd = strs[0];
 var mm = strs[1];
 var yy = strs[2];

 var d = new Date();
 var ds = d.getDate();
 var ms = d.getMonth();
 var ys = d.getFullYear();
 var accepted_age = 18;

 var days = ((accepted_age * 12) * 30) + (ms * 30) + ds;
 var age = (((ys - yy) * 12) * 30) + ((12 - mm) * 30) + parseInt(30 - dd);

 if((days - age) &lt;= '0'){
 console.log((days - age));
 alert('You are at-least ' + accepted_age);
 }else{
 console.log((days - age));
 alert('You are not at-least ' + accepted_age);
 }
}
</code></pre>

blocks|key|1257601|text|这是我的修改：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1257602|++function+calculate_age(date)+{
+++++var+today+=+new+Date();
+++++var+today_month+=+today.getMonth()+%2B+1;+//STRANGE+NUMBERING+//January+is+0!
+++++var+age+=+today.getYear()+-+date.getYear();

+++++if+((today_month+>+date.getMonth()+%7C%7C+((today_month+==+date.getMonth())+&&+(today.getDate()+<+date.getDate()))))+{
+++++++age--;
+++++}

++++return+age;
++};|code-block|syntax|javascript|1257603|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

This is my modification: 

<pre><code> function calculate_age(date) {
 var today = new Date();
 var today_month = today.getMonth() + 1; //STRANGE NUMBERING //January is 0!
 var age = today.getYear() - date.getYear();

 if ((today_month &gt; date.getMonth() || ((today_month == date.getMonth()) &amp;&amp; (today.getDate() &lt; date.getDate())))) {
 age--;
 }

 return age;
 };
</code></pre>

blocks|key|3481610|text|对我来说，这是最优雅的方式：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3481611|​|3481612|const+getAge+=+(birthDateString)+=>+{
++const+today+=+new+Date();
++const+birthDate+=+new+Date(birthDateString);

++const+yearsDifference+=+today.getFullYear()+-+birthDate.getFullYear();

++if+(
++++today.getMonth()+<+birthDate.getMonth()+%7C%7C
++++(today.getMonth()+===+birthDate.getMonth()+&&+today.getDate()+<+birthDate.getDate())
++)+{
++++return+yearsDifference+-+1;
++}

++return+yearsDifference;
};

console.log(getAge('2018-03-12'));|code-block|syntax|javascript|3481613|3481614|entityMap^0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|L|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|M|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|N|8|@]|9|@]|A|$G|H]]|$1|I|3|C|5|6|7|O|8|@]|9|@]|A|$]]|$1|J|3|-4|5|6|7|P|8|@]|9|@]|A|$]]]|K|$]]

That's the most elegant way for me:

<div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="true">
<div class="snippet-code">
<pre class="snippet-code-js lang-js prettyprint-override"><code>const getAge = (birthDateString) =&gt; {
 const today = new Date();
 const birthDate = new Date(birthDateString);

 const yearsDifference = today.getFullYear() - birthDate.getFullYear();

 if (
 today.getMonth() &lt; birthDate.getMonth() ||
 (today.getMonth() === birthDate.getMonth() &amp;&amp; today.getDate() &lt; birthDate.getDate())
 ) {
 return yearsDifference - 1;
 }

 return yearsDifference;
};

console.log(getAge('2018-03-12'));</code></pre>
</div>
</div>

blocks|key|1257666|text|我有点晚了，但我发现这是计算生日的最简单的方法。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1257667|希望这能有所帮助。|1257668|​|1257669|function+init()+{
++writeYears("myage",+0,+Age());

}

function+Age()+{
++var+birthday+=+new+Date(1997,+02,+01),+//Year,+month-1+,+day.
++++today+=+new+Date(),
++++one_year+=+1000+*+60+*+60+*+24+*+365;
++return+Math.floor((today.getTime()+-+birthday.getTime())+/+one_year);
}

function+writeYears(id,+current,+maximum)+{
++document.getElementById(id).innerHTML+=+current;

++if+(current+<+maximum)+{
++++setTimeout(function()+{
++++++writeYears(id,+%2B%2Bcurrent,+maximum);
++++},+Math.sin(current+/+maximum)+*+200);
++}
}
init()|code-block|syntax|javascript|1257670|<span+id="myage">|1257671|1257672|entityMap^0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|P|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|Q|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|R|8|@]|9|@]|A|$]]|$1|F|3|G|5|H|7|S|8|@]|9|@]|A|$I|J]]|$1|K|3|L|5|H|7|T|8|@]|9|@]|A|$I|J]]|$1|M|3|E|5|6|7|U|8|@]|9|@]|A|$]]|$1|N|3|-4|5|6|7|V|8|@]|9|@]|A|$]]]|O|$]]

I am a bit too late but I found this to be the simplest way to calculate a birth date.
Hopefully this will help.
<div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
<div class="snippet-code">
<pre class="snippet-code-js lang-js prettyprint-override"><code>function init() {
 writeYears("myage", 0, Age());

}

function Age() {
 var birthday = new Date(1997, 02, 01), //Year, month-1 , day.
 today = new Date(),
 one_year = 1000 * 60 * 60 * 24 * 365;
 return Math.floor((today.getTime() - birthday.getTime()) / one_year);
}

function writeYears(id, current, maximum) {
 document.getElementById(id).innerHTML = current;

 if (current &lt; maximum) {
 setTimeout(function() {
 writeYears(id, ++current, maximum);
 }, Math.sin(current / maximum) * 200);
 }
}
init()</code></pre>
<pre class="snippet-code-html lang-html prettyprint-override"><code>&lt;span id="myage"&gt;&lt;/span&gt;</code></pre>
</div>
</div>

blocks|key|3481711|text|如果年龄只是为了显示目的(可能不是100%25准确)，那么下面的答案是可行的，但至少更容易理解。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3481712|function+age(birthdate){
++return+Math.floor((new+Date().getTime()+-+new+Date(birthdate).getTime())+/+3.154e%2B10)
}|code-block|syntax|javascript|3481713|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

The below answer is the way to go if the age is just for display purposes (Might not be 100% accurate) but atleast it is easier to wrap your head around
<pre class="lang-js prettyprint-override"><code>function age(birthdate){
 return Math.floor((new Date().getTime() - new Date(birthdate).getTime()) / 3.154e+10)
}
</code></pre>

blocks|key|1257707|text|我认为在这种情况下，有时可读性更重要。除非我们正在验证数千个字段，否则这应该足够准确和快速：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1257708|​|1257709|function+is18orOlder(dateString)+{
++const+dob+=+new+Date(dateString);
++const+dobPlus18+=+new+Date(dob.getFullYear()+%2B+18,+dob.getMonth(),+dob.getDate());
++
++return+dobPlus18+.valueOf()+<=+Date.now();
}

//+Testing:
console.log(is18orOlder('01/01/1910'));+//+true
console.log(is18orOlder('01/01/2050'));+//+false

//+When+I'm+posting+this+on+10/02/2020,+so:
console.log(is18orOlder('10/08/2002'));+//+true
console.log(is18orOlder('10/19/2002'))++//+false|code-block|syntax|javascript|1257710|1257711|我喜欢这种方法，而不是使用一个常数来表示一年中有多少毫秒，然后再去处理闰年，等等。只是让内置的日期来完成这项工作。|1257712|更新，发布这段代码，因为你可能会发现它很有用。由于我在输入字段上强制使用了掩码，格式为mm/dd/yyyy，并且已经验证了日期是否有效，因此在我的示例中，这也适用于验证18%2B年份：|offset|length|style|CODE|1257713|+function+is18orOlder(dateString)+{
+++const+[month,+date,+year]+=+value.split('/');
+++return+new+Date(%2Byear+%2B+13,+%2Bmonth,+%2Bdate).valueOf()+<=+Date.now();
}|1257714|entityMap^0|0|0|0|0|0|17|A|0|0^^$0|@$1|2|3|4|5|6|7|V|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|W|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|X|8|@]|9|@]|A|$G|H]]|$1|I|3|C|5|6|7|Y|8|@]|9|@]|A|$]]|$1|J|3|K|5|6|7|Z|8|@]|9|@]|A|$]]|$1|L|3|M|5|6|7|10|8|@$N|11|O|12|P|Q]]|9|@]|A|$]]|$1|R|3|S|5|F|7|13|8|@]|9|@]|A|$G|H]]|$1|T|3|-4|5|6|7|14|8|@]|9|@]|A|$]]]|U|$]]

I believe that sometimes the readability is more important in this case. Unless we are validating 1000s of fields, this should be accurate and fast enough:
<div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
<div class="snippet-code">
<pre class="snippet-code-js lang-js prettyprint-override"><code>function is18orOlder(dateString) {
 const dob = new Date(dateString);
 const dobPlus18 = new Date(dob.getFullYear() + 18, dob.getMonth(), dob.getDate());
 
 return dobPlus18 .valueOf() &lt;= Date.now();
}

// Testing:
console.log(is18orOlder('01/01/1910')); // true
console.log(is18orOlder('01/01/2050')); // false

// When I'm posting this on 10/02/2020, so:
console.log(is18orOlder('10/08/2002')); // true
console.log(is18orOlder('10/19/2002')) // false</code></pre>
</div>
</div>

I like this approach instead of using a constant for how many ms are in a year, and later messing with the leap years, etc. Just letting the built-in Date to do the job.
Update, posting this snippet since one may found it useful. Since I'm enforcing a mask on the input field, to have the format of <code>mm/dd/yyyy</code> and already validating if the date is valid, in my case, this works too to validate 18+ years:
<pre><code> function is18orOlder(dateString) {
 const [month, date, year] = value.split('/');
 return new Date(+year + 13, +month, +date).valueOf() &lt;= Date.now();
}
</code></pre>

blocks|key|3481845|text|这个问题已经超过10年了，没有人回答过他们已经有YYYYMMDD格式的出生日期的提示吗？|type|unstyled|depth|inlineStyleRanges|entityRanges|data|3481846|如果您有一个YYYYMMDD格式的过去日期和当前日期，您可以非常快速地计算它们之间的年数，如下所示：|3481847|var+pastDate+=+'20101030';
var+currentDate+=+'20210622';
var+years+=+Math.floor(+(+currentDate+-+pastDate+)+*+0.0001+);
//+10+(10.9592)|code-block|syntax|javascript|3481848|您可以将当前日期格式化为YYYYMMDD，如下所示：|offset|length|style|CODE|3481849|var+now+=+new+Date();

var+currentDate+=+[
++++now.getFullYear(),
++++('0'+%2B+(now.getMonth()+%2B+1)+).slice(-2),
++++('0'+%2B+now.getDate()+).slice(-2),
].join('');|3481850|entityMap^0|0|0|0|C|8|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|T|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|U|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|V|8|@$K|W|L|X|M|N]]|9|@]|A|$]]|$1|O|3|P|5|F|7|Y|8|@]|9|@]|A|$G|H]]|$1|Q|3|-4|5|6|7|Z|8|@]|9|@]|A|$]]]|R|$]]

This question is over 10 years old an nobody has addressed the prompt that they already have the birth date in YYYYMMDD format?
If you have a past date and the current date both in YYYYMMDD format, you can very quickly calculate the number of years between them like this:
<pre class="lang-js prettyprint-override"><code>var pastDate = '20101030';
var currentDate = '20210622';
var years = Math.floor( ( currentDate - pastDate ) * 0.0001 );
// 10 (10.9592)
</code></pre>
You can get the current date formatted as <code>YYYYMMDD</code> like this:
<pre class="lang-js prettyprint-override"><code>var now = new Date();

var currentDate = [
 now.getFullYear(),
 ('0' + (now.getMonth() + 1) ).slice(-2),
 ('0' + now.getDate() ).slice(-2),
].join('');
</code></pre>

blocks|key|4893426|text|简短准确(但可读性不高)：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|4893427|let+age+=+(bdate,+now+=+new+Date(),+then+=+new+Date(bdate))+=>+now.getFullYear()+-+then.getFullYear()+-+(now+<+new+Date(now.getFullYear(),+then.getMonth(),+then.getDate()));|code-block|syntax|javascript|4893428|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|J|8|@]|9|@]|A|$E|F]]|$1|G|3|-4|5|6|7|K|8|@]|9|@]|A|$]]]|H|$]]

Short and accurate (but not super readable):
<pre><code>let age = (bdate, now = new Date(), then = new Date(bdate)) =&gt; now.getFullYear() - then.getFullYear() - (now &lt; new Date(now.getFullYear(), then.getMonth(), then.getDate()));
</code></pre>

How can I calculate an age in years, given a birth date of format YYYYMMDD? Is it possible using the <code>Date()</code> function?

I am looking for a better solution than the one I am using now:

<div class="snippet" data-lang="js" data-hide="false" data-console="true" data-babel="false">
<div class="snippet-code">
<pre class="snippet-code-js lang-js prettyprint-override"><code>var dob = '19800810';
var year = Number(dob.substr(0, 4));
var month = Number(dob.substr(4, 2)) - 1;
var day = Number(dob.substr(6, 2));
var today = new Date();
var age = today.getFullYear() - year;
if (today.getMonth() &lt; month || (today.getMonth() == month &amp;&amp; today.getDate() &lt; day)) {
 age--;
}
alert(age);</code></pre>
</div>
</div>

Calculate age given the birth date in the format YYYYMMDD

翻译质量差，导致语言生硬或混乱。

没有提供实际的解决方法或示例。

解答不清晰，无法理解或解决问题。

页面排版不美观，阅读体验差。

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给定出生日期格式为YYYYMMDD，如何以年为单位计算年龄？可以使用Date()函数吗？我正在寻找比我现在使用的解决方案更好的解决方案：​var dob = '19800810';var year = Number(dob.substr(0, 4));var month = Number(dob.substr(4, 2...

问根据出生日期计算年龄，格式为YYYYMMDD
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问根据出生日期计算年龄，格式为YYYYMMDDEN