ECMAScript6 new value-added comparison function Object. is, ecmascript6

ECMAScript6 new value-added comparison function Object. is, ecmascript6

Before that, we use the equal sign "=" or equal sign "=" to compare values, and the third sign is more strict. If the two types are different, false is returned immediately.

In addition, there is only one value that is not equal to itself. It is NaN

Now ES6 adds an Object. is, which makes the comparison operation more chaotic. In most cases, Object. is equivalent to "=", as shown below:

1 = 1 // trueObject. is (1, 1) // true 'A' = 'A' // trueObject. is ('A', 'A') // true = true // trueObject. is (true, true) // true null === null // trueObject. is (null, null) // true undefined === undefined // trueObject. is (undefined, undefined) // true

But for NaN, 0, + 0,-0, it is different from "="

NaN = NaN // falseObject. is (NaN, NaN) // true 0 ===-0 // trueObject. is (0,-0) // false-0 = + 0 // trueObject. is (-0, + 0) // false

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