原网页 http://www.web-jia.com/view.php?a=23?

这个typeof我也用过好多次了，经常会忘记这次特意记录一下

Undefined 	"undefined"
Null 		"object" (see below)
Boolean 	"boolean"
Number 		"number"
String 		"string"
Symbol 		(new in ECMAScript 2015) 	"symbol"
Host object 	(provided by the JS environment) 	Implementation-dependent
Function object (implements [[Call]] in ECMA-262 terms) 	"function"
Any other object "object"

其中有一条要记录一下
typeof null === ‘object‘;

javascript的typeof使用