javascript: public array with object

Question

(sorry for my english=/) I create an array when 'onload'.

(this:

var $ = {
    ratio: 0.7,
    screen: 500,
    margin: 10,
    canvas: document.getElementById("canvas"),
    ctx: document.getElementById("canvas").getContext("2d"),
}

and $.canvas and $.ctx is give 'null'. this work if i rewrite it

...
canvas: function(){return document.getElementById("canvas")}
...

but if i want to call this the variable looks like this $.canvas () how can i make this variable without '()'???

possible duplicate of [Why does jQuery or a DOM method such as \`getElementById\` not find the element?](http://stackoverflow.com/questions/14028959/why-does-jquery-or-a-dom-method-such-as-getelementbyid-not-find-the-element) — Felix Kling, Feb 21 '13 at 17:34

score 2 · Answer 1 · answered Feb 21 '13 at 17:26

2

Try this:

window.onload = function(){
    window.$ = {
        ratio: 0.7,
        screen: 500,
        margin: 10,
        canvas: document.getElementById("canvas"),
        ctx: document.getElementById("canvas").getContext("2d"),
    }
}

answered Feb 21 '13 at 17:26

karaxuna

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score 1 · Accepted Answer · answered Feb 21 '13 at 17:32

Looks like it's a problem with the scope of your $ variable. By declaring it with the var keyword inside the window.onload function, its scope is the local function and not the global scope.

You could define it outside of the onload function instead:

var $; // in the global scope

window.onload = function(){
    $ = {
        ratio: 0.7,
        screen: 500,
        margin: 10,
        canvas: document.getElementById("canvas"),
        ctx: document.getElementById("canvas").getContext("2d")
    };

    console.log($.canvas);
    console.log($.ctx);
};

By declaring it in the global scope, it can be accessed from outside of the onload function.

Fiddle

I don't think it's a scope problem. OP says it works if he assigns a function to `$.canvas`. If it was a scope problem, then the error would be something like `Cannot read property 'canvas' of undefined`. — Felix Kling, Feb 21 '13 at 17:35

javascript: public array with object

2 Answers2