blocks|key|1056935|text|在JavaScript中，变量永远不会是整数类型-它不区分不同类型的数字。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1056936|您可以测试变量是否包含数字，以及该数字是否为整数。|1056937|(typeof+foo+===+"number")+&&+Math.floor(foo)+===+foo|code-block|syntax|javascript|1056938|如果变量可能是一个包含整数的字符串，而您想要查看情况是否是这样：|1056939|foo+==+parseInt(foo,+10)|1056940|entityMap^0|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|O|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|P|8|@]|9|@]|A|$]]|$1|D|3|E|5|F|7|Q|8|@]|9|@]|A|$G|H]]|$1|I|3|J|5|6|7|R|8|@]|9|@]|A|$]]|$1|K|3|L|5|F|7|S|8|@]|9|@]|A|$G|H]]|$1|M|3|-4|5|6|7|T|8|@]|9|@]|A|$]]]|N|$]]

A variable will never be an integer type in JavaScript — it doesn't distinguish between different types of Number.

You can test if the variable contains a number, and if that number is an integer. 

<pre><code>(typeof foo === "number") &amp;&amp; Math.floor(foo) === foo
</code></pre>

If the variable might be a string containing an integer and you want to see if that is the case: 

<pre><code>foo == parseInt(foo, 10)
</code></pre>

blocks|key|842369|text|尝试以下代码：|type|unstyled|depth|inlineStyleRanges|entityRanges|data|842370|+alert(typeof(1)+==+"number");|code-block|syntax|javascript|842371|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 code:

<pre><code> alert(typeof(1) == "number");
</code></pre>

blocks|key|1057007|text|如果一个数的模%251是0，那么它就是一个整数-|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1057008|function+isInt(n){
++++return+(typeof+n==+'number'+&&+n%251==+0);
}|code-block|syntax|javascript|1057009|这只是javascript获得的最好的结果--比如说%2B-+10到15。|1057010|isInt(Math.pow(2,50)%2B.1)返回true，Math.pow(2,50)%2B.1+==+Math.pow(2,50)也返回|offset|length|style|CODE|1057011|entityMap^0|0|0|0|0|O|Q|4|V|Z|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]]|$1|G|3|H|5|6|7|S|8|@]|9|@]|A|$]]|$1|I|3|J|5|6|7|T|8|@$K|U|L|V|M|N]|$K|W|L|X|M|N]|$K|Y|L|Z|M|N]]|9|@]|A|$]]|$1|O|3|-4|5|6|7|10|8|@]|9|@]|A|$]]]|P|$]]

A number is an integer if its modulo %1 is 0-

<pre><code>function isInt(n){
 return (typeof n== 'number' &amp;&amp; n%1== 0);
}
</code></pre>

This is only as good as javascript gets- say +- ten to the 15th. 

<code>isInt(Math.pow(2,50)+.1)</code> returns <code>true</code>, as does
<code>Math.pow(2,50)+.1 == Math.pow(2,50)</code>

blocks|key|1057062|text|我知道你对整数感兴趣，所以我不会再回答这个问题，但是如果你想检查浮点数，你可以这样做。|type|unstyled|depth|inlineStyleRanges|entityRanges|data|1057063|function+isFloat(+x+)
{
++++return+(+typeof+x+===+"number"+&&+Math.abs(+x+%25+1+)+>+0);
}|code-block|syntax|javascript|1057064|注意:这可能会将以.0结尾的数字(或任何逻辑上等价的0)视为整数。在这种情况下，它实际上需要出现浮点精度错误才能检测到浮点值。|offset|length|style|CODE|1057065|例如。|1057066|alert(isFloat(5.2));+++//returns+true
alert(isFloat(5));+++++//returns+false
alert(isFloat(5.0));+++//return+could+be+either+true+or+false|1057067|entityMap^0|0|0|9|2|Q|1|0|0|0^^$0|@$1|2|3|4|5|6|7|S|8|@]|9|@]|A|$]]|$1|B|3|C|5|D|7|T|8|@]|9|@]|A|$E|F]]|$1|G|3|H|5|6|7|U|8|@$I|V|J|W|K|L]|$I|X|J|Y|K|L]]|9|@]|A|$]]|$1|M|3|N|5|6|7|Z|8|@]|9|@]|A|$]]|$1|O|3|P|5|D|7|10|8|@]|9|@]|A|$E|F]]|$1|Q|3|-4|5|6|7|11|8|@]|9|@]|A|$]]]|R|$]]

I know you're interested in Integer numbers so I won't re answer that but if you ever wanted to check for Floating Point numbers you could do this. 

<pre><code>function isFloat( x )
{
 return ( typeof x === "number" &amp;&amp; Math.abs( x % 1 ) &gt; 0);
}
</code></pre>

Note: This MAY treat numbers ending in <code>.0</code> (or any logically equivalent number of <code>0</code>'s) as an INTEGER. It actually needs a floating point precision error to occur to detect the floating point values in that case.

Ex.

<pre><code>alert(isFloat(5.2)); //returns true
alert(isFloat(5)); //returns false
alert(isFloat(5.0)); //return could be either true or false
</code></pre>

blocks|key|842574|text|这些天，ECMAScript+6+(ECMA-262)是“在房子里”。使用Number.isInteger(x)来问你想问的关于x类型的问题：|type|unstyled|depth|inlineStyleRanges|offset|length|style|CODE|entityRanges|data|842575|js>+var+x+=+3
js>+Number.isInteger(x)
true
js>+var+y+=+3.1
js>+Number.isInteger(y)
false|code-block|syntax|javascript|842576|entityMap^0|11|J|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|$]]

These days, ECMAScript 6 (ECMA-262) is "in the house". Use <code>Number.isInteger(x)</code> to ask the question you want to ask with respect to the type of x:

<pre class="lang-js prettyprint-override"><code>js&gt; var x = 3
js&gt; Number.isInteger(x)
true
js&gt; var y = 3.1
js&gt; Number.isInteger(y)
false
</code></pre>

blocks|key|1057176|text|有相当多的实用程序库，比如YourJS，提供了一些函数来判断某个东西是不是数组，是不是整数，或者是很多其他类型。YourJS通过检查该值是否为数字，然后检查该值是否能被1整除来定义isInt：|type|unstyled|depth|inlineStyleRanges|entityRanges|offset|length|data|1057177|function+isInt(x)+{
++return+typeOf(x,+'Number')+&&+x+%25+1+==+0;
}|code-block|syntax|javascript|1057178|上面的代码片段取自this+YourJS+snippet，因此只能工作，因为typeOf是由库定义的。你可以下载一个简约版本的YourJS，它主要只有类型检查功能，比如typeOf()，isInt()和isArray()：http://yourjs.com/snippets/build/34,2|style|CODE|1057179|entityMap|0|LINK|mutability|MUTABLE|url|http://yourjs.com/|1|http://yourjs.com/snippets/34|2|3|http://yourjs.com/snippets/build/34,2^0|D|6|0|2I|5|1|0|0|12|6|2C|8|2L|7|2T|9|9|J|2|33|11|3|0^^$0|@$1|2|3|4|5|6|7|Z|8|@]|9|@$A|10|B|11|1|12]|$A|13|B|14|1|15]]|C|$]]|$1|D|3|E|5|F|7|16|8|@]|9|@]|C|$G|H]]|$1|I|3|J|5|6|7|17|8|@$A|18|B|19|K|L]|$A|1A|B|1B|K|L]|$A|1C|B|1D|K|L]|$A|1E|B|1F|K|L]]|9|@$A|1G|B|1H|1|1I]|$A|1J|B|1K|1|1L]]|C|$]]|$1|M|3|-4|5|6|7|1M|8|@]|9|@]|C|$]]]|N|$O|$5|P|Q|R|C|$S|T]]|U|$5|P|Q|R|C|$S|V]]|W|$5|P|Q|R|C|$S|V]]|X|$5|P|Q|R|C|$S|Y]]]]

Quite a few utility libraries such as <a href="http://yourjs.com" rel="nofollow">YourJS</a> offer functions for determining if something is an array or if something is an integer or a lot of other types as well. YourJS defines <a href="http://yourjs.com/snippets/34" rel="nofollow">isInt</a> by checking if the value is a number and then if it is divisible by 1:

<pre><code>function isInt(x) {
 return typeOf(x, 'Number') &amp;&amp; x % 1 == 0;
}
</code></pre>

The above snippet was taken from <a href="http://yourjs.com/snippets/34" rel="nofollow">this YourJS snippet</a> and thusly only works because <code>typeOf</code> is defined by the library. You can download a minimalistic version of YourJS which mainly only has type checking functions such as <code>typeOf()</code>, <code>isInt()</code> and <code>isArray()</code>: <a href="http://yourjs.com/snippets/build/34,2" rel="nofollow">http://yourjs.com/snippets/build/34,2</a>

blocks|key|842674|text|一种干净的方法|type|unstyled|depth|inlineStyleRanges|entityRanges|data|842675|您可以考虑使用非常小的、无依赖关系的库，如Not。解决所有问题：|offset|length|842676|//+at+the+basic+level+it+supports+primitives
let+number+=+10
let+array+=+[]
not('number',+10)+//+returns+false
not('number',+[])+//+throws+error

//+so+you+need+to+define+your+own:
let+not+=+Object.create(Not)

not.defineType({
++++primitive:+'number',
++++type:+'integer',
++++pass:+function(candidate)+{
++++++++//+pre-ECMA6
++++++++return+candidate.toFixed(0)+===+candidate.toString()
++++++++//+ECMA6
++++++++return+Number.isInteger(candidate)
++++}
})
not.not('integer',+4.4)+//+gives+error+message
not.is('integer',+4.4)+//+returns+false
not.is('integer',+8)+//+returns+true|code-block|syntax|javascript|842677|如果你养成了这样的习惯，你的代码就会变得更强大。Typescript解决了部分问题，但在运行时不起作用，这一点也很重要。|842678|function+test+(string,+boolean)+{
++++//+any+of+these+below+will+throw+errors+to+protect+you
++++not('string',+string)
++++not('boolean',+boolean)

++++//+continue+with+your+code.
}|842679|entityMap|0|LINK|mutability|MUTABLE|url|https://github.com/calvintwr/you-are-not^0|0|L|3|0|0|0|0|0^^$0|@$1|2|3|4|5|6|7|W|8|@]|9|@]|A|$]]|$1|B|3|C|5|6|7|X|8|@]|9|@$D|Y|E|Z|1|10]]|A|$]]|$1|F|3|G|5|H|7|11|8|@]|9|@]|A|$I|J]]|$1|K|3|L|5|6|7|12|8|@]|9|@]|A|$]]|$1|M|3|N|5|H|7|13|8|@]|9|@]|A|$I|J]]|$1|O|3|-4|5|6|7|14|8|@]|9|@]|A|$]]]|P|$Q|$5|R|S|T|A|$U|V]]]]

<h1>A clean approach</h1>
You can consider using a very small, dependency-free library like <a href="https://github.com/calvintwr/you-are-not" rel="nofollow noreferrer">Not</a>. Solves all problems:
<pre class="lang-js prettyprint-override"><code>// at the basic level it supports primitives
let number = 10
let array = []
not('number', 10) // returns false
not('number', []) // throws error

// so you need to define your own:
let not = Object.create(Not)

not.defineType({
 primitive: 'number',
 type: 'integer',
 pass: function(candidate) {
 // pre-ECMA6
 return candidate.toFixed(0) === candidate.toString()
 // ECMA6
 return Number.isInteger(candidate)
 }
})
not.not('integer', 4.4) // gives error message
not.is('integer', 4.4) // returns false
not.is('integer', 8) // returns true
</code></pre>
If you make it a habit, your code will be much stronger. Typescript solves part of the problem but doesn't work at runtime, which is also important.
<pre class="lang-js prettyprint-override"><code>function test (string, boolean) {
 // any of these below will throw errors to protect you
 not('string', string)
 not('boolean', boolean)

 // continue with your code.
}
</code></pre>

How can I check if a variable is currently an integer type? I've looked for some sort of resource for this and I think the === operator is important, but I'm not sure how to check if a variable is an Integer (or an Array for that matter)

type checking in javascript

如何检查变量当前是否为整型？我已经为此寻找了一些资源，我认为===运算符很重要，但我不确定如何检查变量是否为整数(或数组)。

问javascript中的类型检查
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