Strict Mode Not Working?

Strict Mode Not Working?
0.0 0

#1

Why, in this code, is strict mode not doing anything in particular? I should be getting a reference error for an undeclared variable; instead, it seems to be working perfectly.

function foo(){
    "use strict";
    a = 54;
    console.log(a);
    }
foo()

#2

Link: https://jsfiddle.net/y8troLkz/

It works for me …