Input.js

function Input()
{
    this.callbacks =
    {
        keyDown:   [],
        keyUp:     [],
        mouseDown: [],
        mouseUp:   []
    }

    this.addCallbackOnKeyDown = function(code, cb)
    {
        if (this.callbacks.keyDown[code] === undefined)
            this.callbacks.keyDown[code] = [];

        this.callbacks.keyDown[code].push(cb);
    };

    this.addCallbackOnKeyUp = function(code, cb)
    {
        if (this.callbacks.keyUp[code] === undefined)
            this.callbacks.keyUp[code] = [];

        this.callbacks.keyUp[code].push(cb);
    };

    this.addCallbackOnMouseDown = function(code, cb)
    {
        if (this.callbacks.mouseDown[code] === undefined)
            this.callbacks.mouseDown[code] = [];

        this.callbacks.mouseDown[code].push(cb);
    };

    this.addCallbackOnMouseUp = function(code, cb)
    {
        if (this.callbacks.mouseUp[code] === undefined)
            this.callbacks.mouseUp[code] = [];

        this.callbacks.mouseUp[code].push(cb);
    };

    this.notifyKeyDown = function(code)
    {
        if (this.callbacks.keyDown[code] !== undefined)
            for (var i = 0; i < this.callbacks.keyDown[code].length; ++ i)
                this.callbacks.keyDown[code][i]();
    };

    this.notifyKeyUp = function(code)
    {
        if (this.callbacks.keyUp[code] !== undefined)
            for (var i = 0; i < this.callbacks.keyUp[code].length; ++ i)
                this.callbacks.keyUp[code][i]();
    };

    this.notifyMouseDown = function(code)
    {
        if (this.callbacks.mouseDown[code] !== undefined)
            for (var i = 0; i < this.callbacks.mouseDown[code].length; ++ i)
                this.callbacks.mouseDown[code][i]();
    };

    this.notifyMouseUp = function(code)
    {
        if (this.callbacks.mouseUp[code] !== undefined)
            for (var i = 0; i < this.callbacks.mouseUp[code].length; ++ i)
                this.callbacks.mouseUp[code][i]();
    };
}