better approach of finding a variable is function?

Question

Which one is better approach to find whether a variable is of type function

typeof(methodName) == typeof(Function)

or

typeof methodName === 'function'

Answer 1

There are two things going on here:

1. Parentheses — typeof is an operator, not a function, don't use them
2. Comparing to 'function' or typeof Function (which will always return 'function' unless someone is screwing around and overwriting native objects). Use the string, it requires less work and isn't subject to the aforementioned screwing around.

i.e. Use:

typeof methodName === 'function'

Answer 2

The second one has better performance and used in many javascript library