Scope chains in object literals

Question

var x = 9;
var mod = {
    x: 81,
    assign: function(){
        this.x = 9;
        x = 3;
    },
    checkVars: function(){
        alert(x + " - " + this.x );
    }
};

mod.checkVars(); //9 - 81

mod.assign();
mod.checkVars(); //3 - 9

alert(x); //3

Please explain how does scope chains set themselves here. And why does scope resolution for x in checkVars and assign skip the object mod?

Answer 1

Variables and object properties are not the same thing. Variables are part of scope chains, properties are not. The only variables in scope of assign and checkVars are x and mod. The properties of mod are only visible from within those methods via this.propName (or mod.propName).