What "this" references, inside inner functions.

thisThat.js

var x = 1;

function Foo() {
    this.x = 2;
    function bar() {
        console.log(this.x); //=> 1
    }
    bar();

    var zop = function() {
        console.log(this.x); //=> 1
    }
    zop();

    var that = this;
    function fez() {
        console.log(that.x); //=> 2
    }
    fez();
}

new Foo();