Function can be declared in ecma 6 script blocked scoped, without hoisting. 
Example:

"use strict";
var foo = function () {return 0}
console.log(foo());         // 0
{
    function foo () { return 1 }
    console.log(foo());     // 1
    {
        function foo () { return 2 }
        console.log(foo()); // 2
    }
    console.log(foo());     // 1
}
console.log(foo());         // 0


In this code there are defined 3 function foo, not one.