blocks|key|1460638|text|if+(date1.getTime()+>+date2.getTime())+{
++++alert("The+first+date+is+after+the+second+date!");
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1460639|Reference+to+Date+object|unstyled|offset|length|1460640|entityMap|0|LINK|mutability|MUTABLE|url|https://developer.mozilla.org/en/Core_JavaScript_1.5_Reference/Global_Objects/Date^0|0|0|O|0|0^^$0|@$1|2|3|4|5|6|7|Q|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|R|8|@]|9|@$G|S|H|T|1|U]]|A|$]]|$1|I|3|-4|5|F|7|V|8|@]|9|@]|A|$]]]|J|$K|$5|L|M|N|A|$O|P]]]]

<pre><code>if (date1.getTime() &gt; date2.getTime()) {
 alert("The first date is after the second date!");
}
</code></pre>

<a href="https://developer.mozilla.org/en/Core_JavaScript_1.5_Reference/Global_Objects/Date" rel="noreferrer">Reference to Date object</a>

blocks|key|1676065|text|new+Date('1945/05/09').valueOf()+<+new+Date('2011/05/09').valueOf()|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1676066|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>new Date('1945/05/09').valueOf() &lt; new Date('2011/05/09').valueOf()
</code></pre>

blocks|key|1460803|text|可以使用与其他数据类型相同的比较运算符来比较JavaScript的日期：>、<、<=、>=、==、!=、===、!==。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1460804|如果你有两个日期A和B，如果A比B更早回到过去，那么A|1460805|但听起来您遇到的问题是将字符串转换为日期。只需将字符串作为新日期的参数传递即可：|1460806|
|1460807|var+someDate+=+new+Date("12/03/2008");|code-block|syntax|javascript|1460808|1460809|或者，如果您想要的字符串是表单域的值，看起来可能是这样：|1460810|1460811|var+someDate+=+new+Date(document.form1.Textbox2.value);|1460812|1460813|如果该字符串不是JavaScript识别为日期的内容，您仍将获得一个日期对象，但它将是“无效的”。与其他日期的任何比较都将返回false。当转换为字符串时，它将变成“无效日期”。它的getTime()函数将返回NaN，对日期本身调用isNaN()将返回true；这是检查字符串是否为有效日期的简单方法。|1460814|1460815|1460816|entityMap^0|0|0|0|0|0|0|0|0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|Z|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|10|8|@]|9|@]|A|$]]|$1|D|3|E|5|6|7|11|8|@]|9|@]|A|$]]|$1|F|3|G|5|6|7|12|8|@]|9|@]|A|$]]|$1|H|3|I|5|J|7|13|8|@]|9|@]|A|$K|L]]|$1|M|3|G|5|6|7|14|8|@]|9|@]|A|$]]|$1|N|3|O|5|6|7|15|8|@]|9|@]|A|$]]|$1|P|3|G|5|6|7|16|8|@]|9|@]|A|$]]|$1|Q|3|R|5|J|7|17|8|@]|9|@]|A|$K|L]]|$1|S|3|G|5|6|7|18|8|@]|9|@]|A|$]]|$1|T|3|U|5|6|7|19|8|@]|9|@]|A|$]]|$1|V|3|G|5|6|7|1A|8|@]|9|@]|A|$]]|$1|W|3|-4|5|6|7|1B|8|@]|9|@]|A|$]]|$1|X|3|-4|5|6|7|1C|8|@]|9|@]|A|$]]]|Y|$]]

JavaScript's dates can be compared using the same comparison operators the rest of the data types use: >, &lt;, &lt;=, >=, ==, !=, ===, !==. 

If you have two dates A and B, then A &lt; B if A is further back into the past than B.

But it sounds like what you're having trouble with is turning a string into a date. You do that by simply passing the string as an argument for a new Date:

<pre><code>var someDate = new Date("12/03/2008");
</code></pre>

or, if the string you want is the value of a form field, as it seems it might be:

<pre><code>var someDate = new Date(document.form1.Textbox2.value);
</code></pre>

Should that string not be something that JavaScript recognizes as a date, you will still get a Date object, but it will be "invalid". Any comparison with another date will return false. When converted to a string it will become "Invalid Date". Its getTime() function will return NaN, and calling isNaN() on the date itself will return true; that's the easy way to check if a string is a valid date.

blocks|key|1675813|text|可以对Date对象使用getTime()方法来获取相对于1970年1月1日的时间戳(以毫秒为单位)。如果您将两个日期转换为整数时间戳，则可以通过减去它们来比较差异。结果将以毫秒为单位，因此您只需除以1000表示秒，然后除以60表示分钟，依此类推。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1675814|entityMap^0|0^^$0|@$1|2|3|4|5|6|7|D|8|@]|9|@]|A|$]]|$1|B|3|-4|5|6|7|E|8|@]|9|@]|A|$]]]|C|$]]

You can use the getTime() method on a Date object to get the timestamp (in milliseconds) relative to January 1, 1970. If you convert your two dates into integer timestamps, you can then compare the difference by subtracting them. The result will be in milliseconds so you just divide by 1000 for seconds, then 60 for minutes, etc.

blocks|key|1675982|text|我宁愿使用Date+valueOf方法，而不是使用===或!==|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1675983|看起来===是在比较内部对象的引用，而不是日期。|1675984|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|F|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|G|8|@]|9|@]|A|$]]|$1|D|3|-4|5|6|7|H|8|@]|9|@]|A|$]]]|E|$]]

I would rather use the Date valueOf method instead of === or !==

Seems like === is comparing internal Object's references and nothing concerning date.

blocks|key|1461084|text|function+fn_DateCompare(DateA,+DateB)+{+++++//+this+function+is+good+for+dates+>+01/01/1970

++++var+a+=+new+Date(DateA);
++++var+b+=+new+Date(DateB);

++++var+msDateA+=+Date.UTC(a.getFullYear(),+a.getMonth()%2B1,+a.getDate());
++++var+msDateB+=+Date.UTC(b.getFullYear(),+b.getMonth()%2B1,+b.getDate());

++++if+(parseFloat(msDateA)+<+parseFloat(msDateB))
++++++return+-1;++//+lt
++++else+if+(parseFloat(msDateA)+==+parseFloat(msDateB))
++++++return+0;++//+eq
++++else+if+(parseFloat(msDateA)+>+parseFloat(msDateB))
++++++return+1;++//+gt
++++else
++++++return+null;++//+error
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1461085|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 fn_DateCompare(DateA, DateB) { // this function is good for dates &gt; 01/01/1970

 var a = new Date(DateA);
 var b = new Date(DateB);

 var msDateA = Date.UTC(a.getFullYear(), a.getMonth()+1, a.getDate());
 var msDateB = Date.UTC(b.getFullYear(), b.getMonth()+1, b.getDate());

 if (parseFloat(msDateA) &lt; parseFloat(msDateB))
 return -1; // lt
 else if (parseFloat(msDateA) == parseFloat(msDateB))
 return 0; // eq
 else if (parseFloat(msDateA) &gt; parseFloat(msDateB))
 return 1; // gt
 else
 return null; // error
}
</code></pre>

blocks|key|1460926|text|您可以尝试添加以下脚本代码来实现这一点：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1460927|if(CompareDates(smallDate,largeDate,'-')+==+0)+{
++++alert('Selected+date+must+be+current+date+or+previous+date!');
return+false;
}

function+CompareDates(smallDate,largeDate,separator)+{
++++var+smallDateArr+=+Array();
++++var+largeDateArr+=+Array();+
++++smallDateArr+=+smallDate.split(separator);
++++largeDateArr+=+largeDate.split(separator);++
++++var+smallDt+=+smallDateArr[0];
++++var+smallMt+=+smallDateArr[1];
++++var+smallYr+=+smallDateArr[2];++
++++var+largeDt+=+largeDateArr[0];
++++var+largeMt+=+largeDateArr[1];
++++var+largeYr+=+largeDateArr[2];

++++if(smallYr>largeYr)+
++++++++return+0;
else+if(smallYr<=largeYr+&&+smallMt>largeMt)
++++return+0;
else+if(smallYr<=largeYr+&&+smallMt==largeMt+&&+smallDt>largeDt)
++++return+0;
else+
++++return+1;
}++|code-block|syntax|javascript|1460928|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 could try adding the following script code to implement this:

<pre><code>if(CompareDates(smallDate,largeDate,'-') == 0) {
 alert('Selected date must be current date or previous date!');
return false;
}

function CompareDates(smallDate,largeDate,separator) {
 var smallDateArr = Array();
 var largeDateArr = Array(); 
 smallDateArr = smallDate.split(separator);
 largeDateArr = largeDate.split(separator); 
 var smallDt = smallDateArr[0];
 var smallMt = smallDateArr[1];
 var smallYr = smallDateArr[2]; 
 var largeDt = largeDateArr[0];
 var largeMt = largeDateArr[1];
 var largeYr = largeDateArr[2];

 if(smallYr&gt;largeYr) 
 return 0;
else if(smallYr&lt;=largeYr &amp;&amp; smallMt&gt;largeMt)
 return 0;
else if(smallYr&lt;=largeYr &amp;&amp; smallMt==largeMt &amp;&amp; smallDt&gt;largeDt)
 return 0;
else 
 return 1;
} 
</code></pre>

blocks|key|1676180|text|您可以尝试使用此代码检查格式为MM/DD/YYYY的两个日期中哪个日期值最高：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1676181|function+d_check()+{
++++var+dl_sdt=document.getElementIdBy("date_input_Id1").value;+//date+one
++++var+dl_endt=document.getElementIdBy("date_input_Id2").value;+//date+two

++++if((dl_sdt.substr(6,4))+>+(dl_endt.substr(6,4)))+{
++++++++alert("first+date+is+greater");
++++++++return+false;
++++}

++++else+if((((dl_sdt.substr(0,2))+>+(dl_endt.
++++++++substr(0,2)))&&(frdt(dl_sdt.substr(3,2))+>+(dl_endt.substr(3,2))))%7C%7C
++++++++(((dl_sdt.substr(0,2))+>+(dl_endt.substr(0,2)))&&
++++++++((dl_sdt.substr(3,2))+<+(dl_endt.substr(3,2))))%7C%7C
++++++++(((dl_sdt.substr(0,2))+==+(dl_endt.substr(0,2)))&&((dl_sdt.substr(3,2))+>+
++++++++(dl_endt.substr(3,2)))))+{
++++++++++++alert("first+date+is+greater");
++++++++return+false;
++++}

++++alert("second+date+is+digher");
++++return+true;
}|code-block|syntax|javascript|1676182|/*for+checking+this....create+a+form并给出id+to+inputs.The+date+inputs.The+date格式应该是mm/dd/yyyy或mm-dd-yyyy或mm:dd:yyyy或mm.dd.yyyy，如下所示。*/|1676183|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|$]]

You can try this code for checking which date value is the highest from two dates with a format MM/DD/YYYY:

<pre><code>function d_check() {
 var dl_sdt=document.getElementIdBy("date_input_Id1").value; //date one
 var dl_endt=document.getElementIdBy("date_input_Id2").value; //date two

 if((dl_sdt.substr(6,4)) &gt; (dl_endt.substr(6,4))) {
 alert("first date is greater");
 return false;
 }

 else if((((dl_sdt.substr(0,2)) &gt; (dl_endt.
 substr(0,2)))&amp;&amp;(frdt(dl_sdt.substr(3,2)) &gt; (dl_endt.substr(3,2))))||
 (((dl_sdt.substr(0,2)) &gt; (dl_endt.substr(0,2)))&amp;&amp;
 ((dl_sdt.substr(3,2)) &lt; (dl_endt.substr(3,2))))||
 (((dl_sdt.substr(0,2)) == (dl_endt.substr(0,2)))&amp;&amp;((dl_sdt.substr(3,2)) &gt; 
 (dl_endt.substr(3,2))))) {
 alert("first date is greater");
 return false;
 }

 alert("second date is digher");
 return true;
}
</code></pre>

/*for checking this....create a form and give id's to two date inputs.The date format should be mm/dd/yyyy or mm-dd-yyyy or mm:dd:yyyy or mm.dd.yyyy like this. */

blocks|key|1461089|text|++++function+validateform()
++++{
+++++if+(trimAll(document.getElementById("<%25=txtFromDate.ClientID+%25>").value)+!=+"")+{
+++if+(!isDate(trimAll(document.getElementById("<%25=txtFromDate.ClientID+%25>").value)))
+++++++++msg+=+msg+%2B+"<li>Please+enter+valid+From+Date+in+mm/dd/yyyy+format\n";
+++else+{
+++++++var+toDate+=+new+Date();
+++++++var+txtdate+=+document.getElementById("<%25=txtFromDate.ClientID+%25>").value;
+++++++var+d1+=+new+Date(txtdate)
+++if+(Date.parse(txtdate)+>+Date.parse(toDate))+{+++++++++++++++++++
+++++++++msg+=+msg+%2B+"<li>From+date+must+be+less+than+or+equal+to+today's+date\n";
+++}
++}
}

+++++if+(trimAll(document.getElementById("<%25=txtToDate.ClientID+%25>").value)+!=+"")+{
++++++++++++if+(!isDate(trimAll(document.getElementById("<%25=txtToDate.ClientID+%25>").value)))
++++++++++++++++msg+=+msg+%2B+"<li>Please+enter+valid+To+Date+in+mm/dd/yyyy+format\n";
++++++++++++else+{
++++++++++++++++var+toDate+=+new+Date();
++++++++++++++++var+txtdate+=+document.getElementById("<%25=txtToDate.ClientID+%25>").value;
++++++++++++++++var+d1+=+new+Date(txtdate)

++++++++++++++++if+(Date.parse(txtdate)+>+Date.parse(toDate))+{
++++++++++++++++++++msg+=+msg+%2B+"<li>To+date+must+be+less+than+or+equal+to+today's+date\n";+
++++++++++++++++++}
+++++++++++++++++}
++++++++++++++++}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1461090|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 validateform()
 {
 if (trimAll(document.getElementById("&lt;%=txtFromDate.ClientID %&gt;").value) != "") {
 if (!isDate(trimAll(document.getElementById("&lt;%=txtFromDate.ClientID %&gt;").value)))
 msg = msg + "&lt;li&gt;Please enter valid From Date in mm/dd/yyyy format\n";
 else {
 var toDate = new Date();
 var txtdate = document.getElementById("&lt;%=txtFromDate.ClientID %&gt;").value;
 var d1 = new Date(txtdate)
 if (Date.parse(txtdate) &gt; Date.parse(toDate)) { 
 msg = msg + "&lt;li&gt;From date must be less than or equal to today's date\n";
 }
 }
}

 if (trimAll(document.getElementById("&lt;%=txtToDate.ClientID %&gt;").value) != "") {
 if (!isDate(trimAll(document.getElementById("&lt;%=txtToDate.ClientID %&gt;").value)))
 msg = msg + "&lt;li&gt;Please enter valid To Date in mm/dd/yyyy format\n";
 else {
 var toDate = new Date();
 var txtdate = document.getElementById("&lt;%=txtToDate.ClientID %&gt;").value;
 var d1 = new Date(txtdate)

 if (Date.parse(txtdate) &gt; Date.parse(toDate)) {
 msg = msg + "&lt;li&gt;To date must be less than or equal to today's date\n"; 
 }
 }
 }
</code></pre>

I would like to compare two dates in javascript. I have been doing some research, but all I can find is how to return the current date. I want to compare 2 separate dates, not related to today. How do I do that. 

<pre><code>var startDate = Date(document.form1.Textbox2);
</code></pre>

How do I do a Date comparison in Javascript?

我想在javascript中比较两个日期。我一直在做一些研究，但我所能找到的就是如何返回当前日期。我想比较两个不同的日期，与今天无关。我该怎么做呢。var startDate = Date(document.form1.Textbox2);

问如何在Javascript中进行日期比较？
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问如何在Javascript中进行日期比较？
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