JavaScript 三重相等和三变量比较

Question

谁能解释一下？

1 == 1        //true, as expected
1 === 1       //true, as expected
1 == 1 == 1   //true, as expected
1 == 1 == 2   //false, as expected
1 === 1 === 2 //false, as expected
1 === 1 === 1 //false? <--

还有一个 bool 逻辑的名称，它以这种方式比较两个以上的数字(我称之为“三变量比较”，但我认为那是错误的...)

Answer 1

这个表达式:

1 === 1 === 1

被评估为:

(1 === 1) === 1

计算括号内的表达式后:

true === 1

并且该表达式在逻辑上是错误的。不过，下面的表达式按预期返回 true:

1 === 1 === true