确定 JavaScript 值是否为“整数”？
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Determine if JavaScript value is an "integer"?
提问by Kaizokupuffball
Possible Duplicate:
Check if a variable contains a numerical value in Javascript?
How do I check if variable is an integer in jQuery?
如何检查变量是否是 jQuery 中的整数？
Example:
例子：
if (id == int) { // Do this }
Im using the following to get the ID from the URL.
我使用以下内容从 URL 获取 ID。
var id = $.getURLParam("id");
But I want to check if the variable is an integer.
但我想检查变量是否是整数。
回答by bardiir
Try this:
尝试这个：
if(Math.floor(id) == id && $.isNumeric(id))
alert('yes its an int!');
$.isNumeric(id)checks whether it's numeric or notMath.floor(id) == idwill then determine if it's really in integer value and not a float. If it's a float parsing it to int will give a different result than the original value. If it's int both will be the same.
$.isNumeric(id)检查它是否是数字，Math.floor(id) == id然后确定它是否真的是整数值而不是浮点数。如果它是一个浮点数，将其解析为 int 将给出与原始值不同的结果。如果它是 int 两者将是相同的。
回答by Aadit M Shah
Here's a polyfill for the Numberpredicate functions:
这是Number谓词函数的 polyfill ：
"use strict";
Number.isNaN = Number.isNaN ||
n => n !== n; // only NaN
Number.isNumeric = Number.isNumeric ||
n => n === +n; // all numbers excluding NaN
Number.isFinite = Number.isFinite ||
n => n === +n // all numbers excluding NaN
&& n >= Number.MIN_VALUE // and -Infinity
&& n <= Number.MAX_VALUE; // and +Infinity
Number.isInteger = Number.isInteger ||
n => n === +n // all numbers excluding NaN
&& n >= Number.MIN_VALUE // and -Infinity
&& n <= Number.MAX_VALUE // and +Infinity
&& !(n % 1); // and non-whole numbers
Number.isSafeInteger = Number.isSafeInteger ||
n => n === +n // all numbers excluding NaN
&& n >= Number.MIN_SAFE_INTEGER // and small unsafe numbers
&& n <= Number.MAX_SAFE_INTEGER // and big unsafe numbers
&& !(n % 1); // and non-whole numbers
All major browsers support these functions, except isNumeric, which is not in the specification because I made it up. Hence, you can reduce the size of this polyfill:
所有主流浏览器都支持这些功能，除了isNumeric，它不在规范中，因为它是我编造的。因此，您可以减小此 polyfill 的大小：
"use strict";
Number.isNumeric = Number.isNumeric ||
n => n === +n; // all numbers excluding NaN
Alternatively, just inline the expression n === +nmanually.
或者，只需n === +n手动内联表达式。
回答by Marc
Use jQuery's IsNumeric method.
使用 jQuery 的 IsNumeric 方法。
http://api.jquery.com/jQuery.isNumeric/
http://api.jquery.com/jQuery.isNumeric/
if ($.isNumeric(id)) {
//it's numeric
}
CORRECTION: that would not ensure an integer. This would:
更正：这不能确保整数。这个会：
if ( (id+"").match(/^\d+$/) ) {
//it's all digits
}
That, of course, doesn't use jQuery, but I assume jQuery isn't actually mandatory as long as the solution works
那当然不使用 jQuery，但我认为只要解决方案有效，jQuery 实际上并不是强制性的
