Object.is vs === [英] Object.is vs ===

问题描述

我偶然发现了使用这种比较的代码示例：

I stumbled upon a code example which was using this comparison:

var someVar = 0;
Object.is(false, someVar); //Returns false 

我知道 false == 0 将是 true 这就是为什么我们有 === 。

I know false == 0 will be true that's why we have ===.

与 === 不同， Object.is 如何？

推荐答案

=== 在JavaScript中称为严格比较运算符。 Object.is 和严格比较运算符的行为完全相同，除了 NaN 和 + 0 / -0 。

=== is called strict comparison operator in JavaScript. Object.is and strict comparison operator behave exactly the same except for NaN and +0/-0.

从MDN：

Object.is（）方法与根据 === 运算符相等而不相同。将 === 运算符（以及 == 运算符）将数值-0和+0作为等于和 Number.NaN 不等于 NaN 。

Object.is() method is not the same as being equal according to the === operator. The === operator (and the == operator as well) treats the number values -0 and +0 as equal and treats Number.NaN as not equal to NaN.

下面的代码突出显示了 === 和 Object.is（）。

Code below highlights the difference between === and Object.is().

console.log(+0 === -0); //true
console.log(Object.is(+0, -0)); //false

console.log(NaN === NaN); // false
console.log(Object.is(NaN, NaN)); //true

console.log(Number.NaN === Number.NaN); // false
console.log(Object.is(Number.NaN, Number.NaN)); // true

console.log(NaN === Number.NaN); // false
console.log(Object.is(NaN, Number.NaN)); // true

您可以找到更多示例这里。

You can find more examples here.

注意： Object.is 是ECMAScript 6提案的一部分，不广泛支持了但是，您可以使用polyfill进行非ES6浏览器，可在上述链接中找到。

Note: Object.is is part of the ECMAScript 6 proposal and not widely supported yet. However you can use polyfill for non-ES6 browsers which can be found in link given above.

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