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This article will explain in detail how js uses typeof. The editor thinks it is very practical, so I share it with you as a reference. I hope you can get something after reading this article.

Typeof

Operator returns a string representing the type of uncalculated Operand, which is reliable in most cases, but of course there are exceptions

Regular expression

Typeof / s / = = 'function'; / / Chrome 1-12, does not conform to ECMAScript 5.1typeof / s / = =' object'; / / Firefox 5 +, complies with ECMAScript 5.1

NULL

Typeof null = = 'object'; / / JavaScript has been like this since the beginning

In the original implementation of JavaScript, the value in JavaScript was represented by a label representing the type and the actual data value. The type label of the object is 0. Because null represents a null pointer (the value is 0x00 on most platforms), the type tag of null also becomes 0Magnetypeof null and returns object incorrectly.

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