javascript operator “in”

Question

I\'m used to python, so

a = [1,2,3]
1 in a # -> True
b = [\"1\", \"2\", \"3\", \"x\"]
\"x\" in b # -> True

Why is it that in JavaScript

Answer 1

Because "x" in b is looking for a property name 'x'. There is none, they are all numerical (but still string) property names, considering it is an array.