blocks|key|1185005|text|怎么样|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1185006|let+isnum+=+/%5E\d%2B$/.test(val);|code-block|syntax|javascript|1185007|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|$]]

how about

<pre class="lang-js prettyprint-override"><code>let isnum = /^\d+$/.test(val);
</code></pre>

blocks|key|1185107|text|string.match(/%5E[0-9]%2B$/)+!=+null;|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1185108|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>string.match(/^[0-9]+$/) != null;
</code></pre>

blocks|key|1185120|text|String.prototype.isNumber+=+function(){return+/%5E\d%2B$/.test(this);}
console.log("123123".isNumber());+//+outputs+true
console.log("%2B12".isNumber());+//+outputs+false|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1185121|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>String.prototype.isNumber = function(){return /^\d+$/.test(this);}
console.log("123123".isNumber()); // outputs true
console.log("+12".isNumber()); // outputs false
</code></pre>

blocks|key|1400705|text|如果你甚至想支持浮点值(点分隔的值)，那么你可以使用这个表达式：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1400706|var+isNumber+=+/%5E\d%2B\.\d%2B$/.test(value);|code-block|syntax|javascript|1400707|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 want to even support for float values (Dot separated values) then you can use this expression : 

<pre><code>var isNumber = /^\d+\.\d+$/.test(value);
</code></pre>

blocks|key|1185390|text|这是另一种有趣的、可读的检查字符串是否只包含数字的方法。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1185391|此方法的工作方式是使用spread+operator将字符串拆分为数组，然后使用every()方法测试数组are+included中的所有元素(字符)是否都位于数字字符串'0123456789'中|offset|length|style|CODE|1185392|​|1185393|const+digits_only+=+string+=>+[...string].every(c+=>+'0123456789'.includes(c));

console.log(digits_only('123'));+//+true
console.log(digits_only('%2B123'));+//+false
console.log(digits_only('-123'));+//+false
console.log(digits_only('123.'));+//+false
console.log(digits_only('.123'));+//+false
console.log(digits_only('123.0'));+//+false
console.log(digits_only('0.123'));+//+false
console.log(digits_only('Hello,+world!'));+//+false|code-block|syntax|javascript|1185394|1185395|entityMap|0|LINK|mutability|MUTABLE|url|https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Spread_syntax|1|https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/every|2|https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/includes^0|0|14|7|2D|C|B|F|0|14|7|1|1H|C|2|0|0|0|0^^$0|@$1|2|3|4|5|6|7|11|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|12|8|@$D|13|E|14|F|G]|$D|15|E|16|F|G]]|9|@$D|17|E|18|1|19]|$D|1A|E|1B|1|1C]|$D|1D|E|1E|1|1F]]|A|$]]|$1|H|3|I|5|6|7|1G|8|@]|9|@]|A|$]]|$1|J|3|K|5|L|7|1H|8|@]|9|@]|A|$M|N]]|$1|O|3|I|5|6|7|1I|8|@]|9|@]|A|$]]|$1|P|3|-4|5|6|7|1J|8|@]|9|@]|A|$]]]|Q|$R|$5|S|T|U|A|$V|W]]|X|$5|S|T|U|A|$V|Y]]|Z|$5|S|T|U|A|$V|10]]]]

Here's another interesting, readable way to check if a string contains only digits.

This method works by splitting the string into an array using the <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Spread_syntax" rel="noreferrer">spread operator</a>, and then uses the <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/Array/every" rel="noreferrer"><code>every()</code></a> method to test whether all elements (characters) in the array <a href="https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/includes" rel="noreferrer">are included</a> in the string of digits <code>'0123456789'</code>:

<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>const digits_only = string =&gt; [...string].every(c =&gt; '0123456789'.includes(c));

console.log(digits_only('123')); // true
console.log(digits_only('+123')); // false
console.log(digits_only('-123')); // false
console.log(digits_only('123.')); // false
console.log(digits_only('.123')); // false
console.log(digits_only('123.0')); // false
console.log(digits_only('0.123')); // false
console.log(digits_only('Hello, world!')); // false</code></pre>
</div>
</div>

blocks|key|1185146|text|这就是你想要的|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1185147|function+isANumber(str){
++return+!/\D/.test(str);
}|code-block|syntax|javascript|1185148|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 what you want

<pre><code>function isANumber(str){
 return !/\D/.test(str);
}
</code></pre>

blocks|key|1185275|text|下面是一个不使用正则表达式的解决方案：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1185276|function+onlyDigits(s)+{
++for+(let+i+=+s.length+-+1;+i+>=+0;+i--)+{
++++const+d+=+s.charCodeAt(i);
++++if+(d+<+48+%7C%7C+d+>+57)+return+false
++}
++return+true
}|code-block|syntax|javascript|1185277|其中48和57分别是"0“和"9”的字符代码。|1185278|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|$]]

Here is a solution without using regular expressions:

<pre><code>function onlyDigits(s) {
 for (let i = s.length - 1; i &gt;= 0; i--) {
 const d = s.charCodeAt(i);
 if (d &lt; 48 || d &gt; 57) return false
 }
 return true
}
</code></pre>

where 48 and 57 are the char codes for "0" and "9", respectively.

blocks|key|1400825|text|function+isNumeric(x)+{
++++return+parseFloat(x).toString()+===+x.toString();
}|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1400826|尽管这将在带有前导或尾随零的字符串上返回false。|unstyled|offset|length|style|CODE|1400827|entityMap^0|0|K|5|0^^$0|@$1|2|3|4|5|6|7|M|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|N|8|@$G|O|H|P|I|J]]|9|@]|A|$]]|$1|K|3|-4|5|F|7|Q|8|@]|9|@]|A|$]]]|L|$]]

<pre><code>function isNumeric(x) {
 return parseFloat(x).toString() === x.toString();
}
</code></pre>

Though this will return <code>false</code> on strings with leading or trailing zeroes.

blocks|key|1400571|text|那么，您可以使用以下正则表达式：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1400572|%5E\d%2B$|code-block|syntax|javascript|1400573|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|$]]

Well, you can use the following regex:

<pre><code>^\d+$
</code></pre>

blocks|key|1400977|text|以防在同一验证中需要整型和浮点型|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1400978|/%5E\d%2B\.\d%2B$%7C%5E\d%2B$/.test(val)|offset|length|style|CODE|1400979|entityMap^0|0|0|S|0^^$0|@$1|2|3|4|5|6|7|J|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|K|8|@$D|L|E|M|F|G]]|9|@]|A|$]]|$1|H|3|-4|5|6|7|N|8|@]|9|@]|A|$]]]|I|$]]

in case you need integer and float at same validation
<code>/^\d+\.\d+$|^\d+$/.test(val)</code>

blocks|key|1185487|text|如果还想包含浮点值，可以使用以下代码|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1185488|theValue=$('#balanceinput').val();
var+isnum1+=+/%5E\d*\.?\d%2B$/.test(theValue);
var+isnum2+=++/%5E\d*\.?\d%2B$/.test(theValue.split("").reverse().join(""));
alert(isnum1%2B'+'%2Bisnum2);|code-block|syntax|javascript|1185489|这将仅测试数字和用'.‘分隔的数字。第一个测试将涵盖0.1和0等值，但也包括.1，它不允许0。所以我提出的解决方案是反转theValue，这样.1将为1，那么相同的正则表达式将不允许它。|1185490|示例：|1185491|+theValue=3.4;+//isnum1=true+,+isnum2=true+
theValue=.4;+//isnum1=true+,+isnum2=false+
theValue=3.;+//isnum1=flase+,+isnum2=true+|1185492|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]]|$1|G|3|H|5|6|7|Q|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|R|8|@]|9|@]|A|$]]|$1|K|3|L|5|D|7|S|8|@]|9|@]|A|$E|F]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

if you want to include float values also you can use the following code 

<pre><code>theValue=$('#balanceinput').val();
var isnum1 = /^\d*\.?\d+$/.test(theValue);
var isnum2 = /^\d*\.?\d+$/.test(theValue.split("").reverse().join(""));
alert(isnum1+' '+isnum2);
</code></pre>

this will test for only digits and digits separated with '.' the first test will cover values such as 0.1 and 0 but also .1 , 
it will not allow 0. so the solution that I propose is to reverse theValue so .1 will be 1. then the same regular expression will not allow it .

example : 

<pre><code> theValue=3.4; //isnum1=true , isnum2=true 
theValue=.4; //isnum1=true , isnum2=false 
theValue=3.; //isnum1=flase , isnum2=true 
</code></pre>

blocks|key|1400951|text|如果您使用jQuery：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1400952|$.isNumeric('1234');+//+true
$.isNumeric('1ab4');+//+false|code-block|syntax|javascript|1400953|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 use jQuery:
<pre><code>$.isNumeric('1234'); // true
$.isNumeric('1ab4'); // false
</code></pre>

blocks|key|1185544|text|这里有一个不使用正则表达式的解决方案|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1185545|const++isdigit=(value)=>{
++++const+val=Number(value)?true:false
++++console.log(val);
++++return+val
}

isdigit("10")//true
isdigit("any+String")//false|code-block|syntax|javascript|1185546|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|$]]

<h1>Here's a Solution without using regex</h1>
<pre class="lang-js prettyprint-override"><code>const isdigit=(value)=&gt;{
 const val=Number(value)?true:false
 console.log(val);
 return val
}

isdigit(&quot;10&quot;)//true
isdigit(&quot;any String&quot;)//false
</code></pre>

blocks|key|1185428|text|c="123".match(/\D/)+==+null+#true
c="a12".match(/\D/)+==+null+#false|type|code-block|depth|inlineStyleRanges|entityRanges|data|syntax|javascript|1185429|如果字符串只包含数字，则返回null|unstyled|1185430|entityMap^0|0|0^^$0|@$1|2|3|4|5|6|7|I|8|@]|9|@]|A|$B|C]]|$1|D|3|E|5|F|7|J|8|@]|9|@]|A|$]]|$1|G|3|-4|5|F|7|K|8|@]|9|@]|A|$]]]|H|$]]

<pre><code>c="123".match(/\D/) == null #true
c="a12".match(/\D/) == null #false
</code></pre>

If a string contains only digits it will return null

I want to check if a <code>string</code> contains only digits. I used this:
<pre><code>var isANumber = isNaN(theValue) === false;

if (isANumber){
 ..
}
</code></pre>
But realized that it also allows <code>+</code> and <code>-</code>. Basically, I want to make sure an <code>input</code> contains ONLY digits and no other characters. Since <code>+100</code> and <code>-5</code> are both numbers, <code>isNaN()</code> is not the right way to go.
Perhaps a regexp is what I need? Any tips?

Check if string contains only digits

jQuery

我想检查string是否只包含数字。我使用了这个：var isANumber = isNaN(theValue) === false;if (isANumber){    ..}但意识到它也允许+和-。基本上，我希望确保input只包含数字，不包含其他字符。因为+100和-5都是数字，所以isNaN()不是正确的方法。也许我需要一个正则表达式？有什么建议吗？

问检查字符串是否只包含数字
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