Javascript Object as Parameter Handling

Question

I have 2 Javascript objects, Limits and Wind, and are trying to call the function on the one object that is a parameter of the other object. The alert is never called and there's no errors in the console. Am I doing this right?

var Limits = {
    minx: 0,
    miny: 0,

    SetMaxLimits: function (x1, x2, y1, y2, zoom) {
        alert('j');
    }
};


var Wind = {
    Data    : Limits,
    Screen  : Limits,
    Rotation: 0,
    CanvasW : 0,
    CanvasH : 0,
    North   : true,
    _Math   : true,

    NormalLimits: function (x,y) {
        Data.SetMaxlimits(0, 0, 0, 0, 0);
    }
};

Wind.NormalLimits(0,0);

Definitely there's an error in console...

Teemu
– Teemu

2014-04-24 17:35:52 +00:00
Commented Apr 24, 2014 at 17:35 — Teemu
– Teemu, Commented Apr 24, 2014 at 17:35
Wow, it was the type. l to L fixed it. Cheers everyone.

Benstof
– Benstof

2014-04-24 17:45:10 +00:00
Commented Apr 24, 2014 at 17:45 — Benstof
– Benstof, Commented Apr 24, 2014 at 17:45

adeneo · Accepted Answer · 2014-04-24 17:34:55Z

4

You have a typo, it's SetMaxLimits, not SetMaxlimits, and you have to reference the object that the Data method is a property of, which in this case could probably be done with this, depending on how the function is called.

var Limits = {
    minx: 0,
    miny: 0,

    SetMaxLimits: function (x1, x2, y1, y2, zoom) {
        alert('j');
    }
};


var Wind = {
    Data    : Limits,
    Screen  : Limits,
    Rotation: 0,
    CanvasW : 0,
    CanvasH : 0,
    North   : true,
    _Math   : true,

    NormalLimits: function () {
        this.Data.SetMaxLimits(0, 0, 0, 0, 0);
    }
};

Wind.NormalLimits();

FIDDLE

answered Apr 24, 2014 at 17:34

adeneo

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2 Comments

xtofl Over a year ago

aren't we craving for case-insensitive identifiers :)

adeneo Over a year ago

@xtofl - nope we are not, case sensitivity suits me just fine !

milagvoniduak · Accepted Answer · 2014-04-24 17:37:40Z

1

It is scoping problem. You are trying to access Data, which is not accessible in the context of the NoarmaLimits function. If you access it through Wind object though it will work.

var Wind = {
    Data    : Limits,
    Screen  : Limits,
    Rotation: 0,
    CanvasW : 0,
    CanvasH : 0,
    North   : true,
    _Math   : true,

    NormalLimits: function () {
        Wind.Data.SetMaxLimits(0, 0, 0, 0, 0);
    }
};

http://jsfiddle.net/PYTcR/

answered Apr 24, 2014 at 17:37

milagvoniduak

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3 Comments

xtofl Over a year ago

I was surprised to see Wind.Data..... But actually it's safer than this.Data.... in @adeno's answer.

adeneo Over a year ago

@xtofl - It's not "safer", it's actually somewhat bad form to reference the literal directly by name inside the literal. When using this as a reference one has to be aware of the context the function is called in, and what value this actually has, but in most cases it will be the object literal unless specifically called with a different value for this (apply, call etc).

milagvoniduak Over a year ago

In my opinion it is better to use "this" keyword, when you are following the prototype pattern. In all other cases I would avoid using "this".

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