function a(){
    var user = "julia98";
    console.log(this.user); //undefined
    console.log(this); //Window
}
a();

var o = {
    user:"julia98",
    fn:function(){
        console.log(this.user);  //julia98
    }
}
o.fn();

var o = {
    a:10,
    b:{
        a:12,
        fn:function(){
            console.log(this.a); //12
        }
    }
}
o.b.fn();

var o = {
    a:10,
    b:{
        // a:12,
        fn:function(){
            console.log(this.a); //undefined
        }
    }
}
o.b.fn();

var o = {
    a:10,
    b:{
        a:12,
        fn:function(){
            console.log(this.a); //undefined
            console.log(this); //window
        }
    }
}
var j = o.b.fn;
j();