为什么1 === 1 === 1为假? [英] Why is 1===1===1 false?

问题描述

在浏览器控制台中，输入1===1将得出true.输入1===1===1会得出false.

In a browser console, entering 1===1 evaluates to true. Entering 1===1===1 evaluates to false.

我认为这是由于语句的评估方式所致:

I assume that this is because of the way the statement is evaluated:

1 === 1 === 1

成为

(1 === 1) === 1

计算结果为

true === 1

是false.

这是正确的吗?如果没有，这种行为的真正原因是什么?

Is this correct? If not, what's the real reason for this behaviour?

推荐答案

是的，您完全正确.在这里，您有两个相等性检查，它们具有相同的运算符优先级.首先进行评估，然后将其结果应用于下一个相等性检查.

Yes, you're exactly right. Here you have two equality checks, which have the same operator precedence. First one evaluates first, then its result applies to the next equality check.

1===1===1与(1===1)===1相同，而(1===1)===1是true===1也是false，因为在这里您可以按值及其类型进行检查. 1==1==1将导致true，因为它仅按值检查相等性，因此1==1==1等于(1==1)==1等于true==1等于true.

1===1===1is the same as (1===1)===1 which is true===1 which is false, because here you check by values AND their types. 1==1==1 will result in true, because it checks equality by values only, so 1==1==1 equal to (1==1)==1 equal to true==1 equal to true.

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