JavaScript 中 != 和 !== 运算符有什么区别？

Question

What is the difference between the !== operator and the != operator in JavaScript? Does it behave similarly to the === operator where it compares both value and type?

Answer 1

Yes, it's the same operator like === , just for in equality:

!== - returns true if the two operands are not identical. This operator will not convert the operands types, and only returns false if they are the same type and value. — Wikibooks

Answer 2

Yes, !== is the strict version of the != operator, no type coercion is done if the operands are of different type:

0 != ''            // false, type coercion made
0 != '0'           // false
false != '0'       // false

0 !== ''           // true, no type coercion
0 !== '0'          // true
false !== '0'      // true

Answer 3

I was about to post this w3schools page , but funnily enough it didn't contain this operator!

At least, the !== is indeed the inverse of === which tests the equality of both type and value.