How to efficiently check if variable is Array or Object

How to efficiently check if variable is Array or Object

a = [1,2,3]

[1, 2, 3]

a.constructor === Object

false

a.constructor === Array

true

a = [1,2,3]

[1, 2, 3]

a = {'name' : 'ggg', 'age': '52'}

Object {name: "ggg", age: "52"}

a.constructor === Array

false

a.constructor === Object

true