（typeof variable ==='boolean'）和（typeof variable =='boolean'）之间有什么区别？

Question

I all, I can't figure out - in type comparison/test - why we usually use :

typeof variable === 'boolean'

...and never see this one :

typeof variable == 'boolean'

As it seems to me that typeof always returns a string value (the type name), I don't understand why we should test the type... of the type string ?

Answer 1

I guess it's just common practice, and it's idiomatic because triple equals compares the types as well; which makes more sense since you're interested in the type. But in practice you aren't going to see a difference in behaviour in this case. Also see this .