CODEWITHSUNDEEP
javascriptdomobject
Nilzone-
Nilzone-

Reputation: 2786

store DOM-elements using objects in Javascript

I'm making a game where I want to store the enemies as an object before loading them into the game.

var that = this;
this.enemies = {
    that.redCar : document.getElementById('red'),   
    that.sportsCar : document.getElementById('sport')
}

But this gives me a syntax error. I thought that.redCar : document.getElementById('red') in an object would be equal to that.redCar = document.getElementById('red') outside of one.

Where am I going wrong?

Upvotes: 0

Views: 2229

Answers (5)

Jackson Ray Hamilton
Jackson Ray Hamilton

Reputation: 9466

You seem to believe that it is necessary to declare the this keyword when assigning properties to a JavaScript object.

While this may be true when defining an object's constructor, like so...

function MyClass() {
    this.color = "blue";
}
var myObj = new MyClass();

...right now, this is not the case.

When you use the "object literal" syntax (var myObj = { /*properties...*/ };), this isn't required; in fact, it isn't allowed.

Here's how you should assign those properties:

this.enemies = {
    redCar: document.getElementById('red'),   
    sportsCar: document.getElementById('sport')
};

Upvotes: 1

Nick Tomlin
Nick Tomlin

Reputation: 29221

Unless there is a different function scope than the one that you listed in your code, there is no need to use this. Just declare an object literal: 

enemies = {
    redCar : document.getElementById('red'),   
    sportsCar : document.getElementById('sport')
}

// example reference
enemies.redCar.className += " active";

Also, be careful with this. Unless you are using this within the scope of a function, you are referring to the window object. Unless you are declaring the above code within a function scope that you have not stated, this refers to the global object.

Upvotes: 0

tckmn
tckmn

Reputation: 59283

When you say this.enemies = { ... }, you are declaring an Object literal that is inside of this, i.e.:

this
  enemies
    redCar: ...
    sportsCar: ...

It doesn't make sense to say that.redCar = ..., because you are already inside enemies. If you want to access it like

this.enemies.redCar

then you can just do this:

this.enemies = {
    redCar : document.getElementById('red'),   
    sportsCar : document.getElementById('sport')
}

And if you want to access it like

this.redCar

then don't use enemies at all, and just do

this.redCar = document.getElementById('red'),   
this.sportsCar = document.getElementById('sport')

Upvotes: 4

jasonslyvia
jasonslyvia

Reputation: 2535

You have to use string as an object key, thus that.redCar is illegal.

Upvotes: 0

hades87
hades87

Reputation: 41

I think is better to declare the variable that as an object, no? You better try with:

var that = new Object();

Instead of:

var that = this;

Or what is the declaration of this?

Upvotes: -1

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