检查函数是否为javascript中的Function类型

Question

Yes, I know there are plenty of posts on this, but I do not understand the selected answer of this post . Particularly, why is it necessary to return object ?

Why wouldn't something like Object.prototype.toString.call(myFunc) be sufficient as described by MDN ?

Answer 1

why is it necessary to return object ?

It's not necessary to do object && , but a shortcut for falsy values that avoids the method call for values such as null . Of course, if you're looking for speed, you probably should go for typeof object == "function"

Why wouldn't something like Object.prototype.toString.call(myFunc) be sufficient?

It is sufficient.

Answer 2

return object && getClass.call(object) == '[object Function]'

This construction simply verifies if object is not null or undefined (generally falsy).
This way it's faster, because JavaScript doesn't evaluate the getClass() call on a falsy object .