爲何你應該使用 Object.is() 進行相等性比較(譯)

Title: Why you should use Object.is() in equality comparison

Author: TarekAlQaddy

Website: https://www.jstips.co/en/javascript/why-you-should-use-Object.is()-in-equality-comparison/

 

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We all know that JavaScript is loosely typed and in some cases it fall behind specially when it comes to equality comparison with ‘==’, comparing with ‘==’ gives unexpected results due to whats called coercion or casting 「converting one of the 2 operands to the other’s type then compare」.

咱們都知道JavaScript是弱類型語言，在某些狀況下，當與「 ==」進行相等性比較時，它特別落後。使用「 ==」進行比較可能會「將2個操做數中的一個強制轉換爲另外一種類型而後進行比較」而產生意外結果。

1 0 == ' ' //true
2 null == undefined //true
3 [1] == true //true

So they provided us with the triple equal operator ‘===’ which is more strict and does not coerce operands, However comparing with ‘===’ is not the best solution you can get:

所以Javascript提供了三等運算符，三等運算符更加嚴格而且不會將操做數進行強制類型轉換。然而三等運算符也不是最好的解決方案，也存在問題：

1 NaN === NaN //false

The great news that in ES6 there is the new ‘Object.is()’ which is better and more precise it has the same features as ‘===’ and moreover it behaves well in some special cases:

好消息是，在ES6中有一個新的「 Object.is（）」，它更好，更精確，它具備與「 ===」相同的功能，並且在某些特殊狀況下，其表現還不錯：

1 Object.is(0 , ' '); //false
2 Object.is(null, undefined); //false
3 Object.is([1], true); //false
4 Object.is(NaN, NaN); //true

Mozilla team doesn’t think that Object.is is 「stricter」 than ‘===’ they say that we should think of how this method deal with NaN, -0 and +0 but overall I think it is now a good practice in real applications.

Mozilla團隊不認爲"Object.is()"比「 ===」更「嚴格」，應該考慮該方法如何處理NaN，-0和+0，但總的來講，我認爲這是一種最佳實踐。

Now this table illustrates..

下表所示：

參考:

Object.is() - JavaScript | MDN

Equality comparisons and sameness