检查变量是否等于相同的变量四舍五入为整数，就像这样:

if(Math.round(data) != data) {
    alert("Variable is not an integer!");
}

这将解决另一个场景(121.)，结束处有一个点

function isInt(value) {
        var ind = value.indexOf(".");
        if (ind > -1) { return false; }

        if (isNaN(value)) {
            return false;
        }

        var x = parseFloat(value);
        return (x | 0) === x;

    }

ECMA-262 6.0 (ES6)标准包括编号。isInteger函数。

为了增加对旧浏览器的支持，我强烈建议使用强大的和社区支持的解决方案:

https://github.com/paulmillr/es6-shim

这是一个纯粹的ES6 JS polyfills库。

注意，这个库需要es5-shim，只需遵循README.md即可。

大整数(bigint)呢?

大多数这些答案在大整数(253或更大)上失败:(x | 0) === x)，测试typeof x === 'number'，常规int函数(例如parseInt)，常规算术在大整数上失败。这可以通过使用BigInt来解决。

我将几个答案编译成一个代码片段以显示结果。对于大整数，大多数完全失败，而其他的则可以，除非传入BigInt类型(例如1n)。我没有包括重复的答案，也没有任何答案，允许小数或不试图测试类型)

// these all fail n = 1000000000000000000000000000000 b = 1n // These all fail on large integers //https://stackoverflow.com/a/14636652/3600709 console.log('fail',1,n === parseInt(n, 10)) //https://stackoverflow.com/a/14794066/3600709 console.log('fail',2,!isNaN(n) && parseInt(Number(n)) == n && !isNaN(parseInt(n, 10))) console.log('fail',2,!isNaN(n) && (parseFloat(n) | 0) === parseFloat(n)) console.log('fail',2,!isNaN(n) && (function(x) { return (x | 0) === x; })(parseFloat(n))) //https://stackoverflow.com/a/21742529/3600709 console.log('fail',3,n == ~~n) //https://stackoverflow.com/a/28211631/3600709 console.log('fail',4,!isNaN(n) && parseInt(n) == parseFloat(n)) //https://stackoverflow.com/a/41854178/3600709 console.log('fail',5,String(parseInt(n, 10)) === String(n)) // These ones work for integers, but not BigInt types (e.g. 1n) //https://stackoverflow.com/a/14636725/3600709 console.log('partial',1,typeof n==='number' && (n%1)===0) // this one works console.log('partial',1,typeof b==='number' && (b%1)===0) // this one fails //https://stackoverflow.com/a/27424770/3600709 console.log('partial',2,Number.isInteger(n)) // this one works console.log('partial',2,Number.isInteger(b)) // this one fails //https://stackoverflow.com/a/14636638/3600709 console.log('partial',3,n % 1 === 0) console.log('partial',3,b % 1 === 0) // gives uncaught type on BigInt

检查类型

如果你真的想测试输入值的类型，以确保它是一个整数，可以使用下面的方法:

function isInt(value) {
    try {
        BigInt(value)
        return !['string','object','boolean'].includes(typeof value)
    } catch(e) {
        return false
    }
}

function isInt(value) { try { BigInt(value) return !['string','object','boolean'].includes(typeof value) } catch(e) { return false } } console.log('--- should be false') console.log(isInt(undefined)) console.log(isInt('')) console.log(isInt(null)) console.log(isInt({})) console.log(isInt([])) console.log(isInt(1.1e-1)) console.log(isInt(1.1)) console.log(isInt(true)) console.log(isInt(NaN)) console.log(isInt('1')) console.log(isInt(function(){})) console.log(isInt(Infinity)) console.log('--- should be true') console.log(isInt(10)) console.log(isInt(0x11)) console.log(isInt(0)) console.log(isInt(-10000)) console.log(isInt(100000000000000000000000000000000000000)) console.log(isInt(1n))

不检查类型

如果你不关心传入类型是否实际上是布尔值、字符串等转换成数字，那么只需使用以下方法:

function isInt(value) {
    try {
        BigInt(value)
        return true
    } catch(e) {
        return false
    }
}

function isInt(value) { try { BigInt(value) return true } catch(e) { return false } } console.log('--- should be false') console.log(isInt(undefined)) console.log(isInt(null)) console.log(isInt({})) console.log(isInt(1.1e-1)) console.log(isInt(1.1)) console.log(isInt(NaN)) console.log(isInt(function(){})) console.log(isInt(Infinity)) console.log('--- should be true') console.log(isInt(10)) console.log(isInt(0x11)) console.log(isInt(0)) console.log(isInt(-10000)) console.log(isInt(100000000000000000000000000000000000000)) console.log(isInt(1n)) // gets converted to number console.log(isInt('')) console.log(isInt([])) console.log(isInt(true)) console.log(isInt('1'))

检查变量是否等于相同的变量四舍五入为整数，就像这样:

if(Math.round(data) != data) {
    alert("Variable is not an integer!");
}

你也可以试试这种方法

var data = 22;
if (Number.isInteger(data)) {
    console.log("integer");
 }else{
     console.log("not an integer");
 }

or

if (data === parseInt(data, 10)){
    console.log("integer");
}else{
    console.log("not an integer");
}