JS中的null, undefined, NaN, false和0

一直都知道，在JS的if判断中，null, undefined, NaN, false, 0, ''都为假，但是：

 

 

null == undefined is true

false == 0 is true

false == '' is true

0 == '' is true

NaN == NaN is false

NaN == 0 is false

NaN == null is false

NaN == false is false

undefined == 0 is false

null == false is false

null == 0 is false

 

null和undefined的值是相同的；false等于0等于''；NaN不等于NaN；NaN，false和null互不相等。