Creating a javascript Object and calling it's method

Question

I have the following code, in one file, but it doesnt seem to work.

I'm basically trying to create an object and try to simply call the object's function and display it, it doesn't do that and I dont know why.

var mice = new Mice(10, 10);
function Mice(posX, posY)
{
    this.x = posX;
    this.y = posY;
    this.moveLeft = function ()
    {
        this.x = x - 1;
    }

    this.moveRight = function ()
    {
        this.x = x + 1;
    }

    this.getXPos = function ()
    {
        return this.x;
    }
}

document.onkeydown = function(e)
{
    //document.getElementById("mainBody").innerHTML = e.keyCode;

    switch(e.keyCode)
    {
    case 37:
        //document.getElementById("mainBody").innerHTML = "you have pressed left";
        mice.moveLeft();
        document.getElementById("mainBody").innerHTML = mice.getXPos();
        break;
        default:
    //do nothing
    break;
    }
}

any help on trying to get this working will be greatly appreciated.

Thanks

Pointy · Accepted Answer · 2013-01-14 15:03:33Z

5

In your "move" functions, you have to consistently refer to this.x:

    this.x = this.x - 1;

Similarly, the "getXPos" function must also:

    return this.x;

answered Jan 14, 2013 at 15:03

Pointy

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1 Comment

guypursey Over a year ago

+1 for mentioning the need to do this (no pun intended) consistently. And for giving examples as to how this should look in the other functions, as well as getXPos().

SLaks · Accepted Answer · 2013-01-14 15:02:34Z

3

return x;

You never made an x variable anywhere.

You mean return this.x;.

answered Jan 14, 2013 at 15:02

SLaks

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2 Comments

Danny Over a year ago

Many thanks for point the error out. However, I've corrected it and it still doesn't work...

apsillers Over a year ago

@Danny You'll also need to do this.x = this.x - 1; (or just this.x -= 1;) and this.x = this.x + 1;.

Loupax · Accepted Answer · 2013-01-14 15:05:01Z

1

There is no x variable in the scope of your getXPos() method. I think you mean to return this.x

answered Jan 14, 2013 at 15:05

Loupax

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