Why do object == this, but object.member != this.member in the realm of Javascript?

Question

Why do object == this, but object.member != this.member in the realm of Javascript?

I currently have an object labeled o along with a reference to it.

Inside the scope of object o, I define a member named m.

Within object o, I execute:

o.m = "blah"

When I try to access m outside of object o:

console.log(o.m)

The output is not "blah". To investigate, I ran:

console.log(this == this.parent.o)

This statement evaluates to true. I am puzzled by this behavior. My browser is Chrome 17.0.963.56 m

UPDATE

I also experimented within object o:

this.m = "blah"
console.log(this.m) // prints "blah"

However, upon exiting that context and running:

console.log(o.m)

The result is different.

Below is the relevant code snippet (refer to this.addEvent("playPauseButtonClicked")):

    // Controller code (singleton)
    function controller() {
        if (window.c) { return window.c; }
        window.c = this;
    ...
    }

javascript

Answer 1

Answer №1

When working within the confines of o and trying to assign a value to m, the correct syntax would be:

this.m = "blah";

It is important to consider that within o, the scope of o may have been set differently, leading to unexpected behavior.

UPDATE 2 -- It seems like the OP has revised their question, so the following code might no longer be applicable -- sigh

UPDATE

A couple of issues have been identified. Firstly:

this.p = new player();

Where your player constructor is defined as:

function player(controller) {
    this.controller = controller;

It appears that you are not passing anything for the controller parameter, resulting in the undefined error for p. Try the following instead:

this.p = new player(this);

Additionally, in your controller constructor, after assigning p as a property of the return object using this.p = new player(this), you should reference it as this.p moving forward; referencing just p will result in an undeclared variable. So

function controller() {
    this.p = new player(this);
    p.changeState();
    console.log(p.state);

should be updated to:

function controller() {
    this.p = new player(this);
    this.p.changeState();
    console.log(this.p.state);

Answer 2

When working within the confines of o and trying to assign a value to m, the correct syntax would be:

this.m = "blah";

It is important to consider that within o, the scope of o may have been set differently, leading to unexpected behavior.

UPDATE 2 -- It seems like the OP has revised their question, so the following code might no longer be applicable -- sigh

UPDATE

A couple of issues have been identified. Firstly:

this.p = new player();

Where your player constructor is defined as:

function player(controller) {
    this.controller = controller;

It appears that you are not passing anything for the controller parameter, resulting in the undefined error for p. Try the following instead:

this.p = new player(this);

Additionally, in your controller constructor, after assigning p as a property of the return object using this.p = new player(this), you should reference it as this.p moving forward; referencing just p will result in an undeclared variable. So

function controller() {
    this.p = new player(this);
    p.changeState();
    console.log(p.state);

should be updated to:

function controller() {
    this.p = new player(this);
    this.p.changeState();
    console.log(this.p.state);

Answer 3

Answer №2

It is essential to declare the variable before using it.

var x = new o; console.log(o.m);

Answer 4

It is essential to declare the variable before using it.

var x = new o; console.log(o.m);

Answer 5

Answer №3

If I were to make a modification:

this.player = new player(this);
this.player.changeState();
console.log(this.player.state);

Here are two key changes:

player should be referenced with this.player instead of just player
The player constructor now requires a controller parameter

Answer 6

If I were to make a modification:

this.player = new player(this);
this.player.changeState();
console.log(this.player.state);

Here are two key changes:

player should be referenced with this.player instead of just player
The player constructor now requires a controller parameter

Why do object == this, but object.member != this.member in the realm of Javascript?

Answer №1

Answer №2

Answer №3

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