Boolean 相关

Boolean(something) 会把里面的变量转化为布尔型

 

当我们用if(something）判断的时候，相当于调用了这个函数

 

转化规则如下

DATA TYPE	VALUES CONVERTED TO TRUE	VALUES CONVERTED TO FALSE
Boolean	true	false
String	Any nonempty string	“” (empty string)
Number	Any nonzero number (including infinity)	0, NaN (See the “NaN” section later in this chapter.)
Object	Any object	null
Undefined	n/a	undefined