arrays of object literal in javascript

Question

I am wondering if i can get the object property using array. I am getting 'undefine' value for this.label[i].xOffset. Any suggestions?

function label() {
    var lbl = this;
    lbl.rText;
    lbl.precision =1;
    lbl.prefix = '';
    lbl.suffix = '';
    lbl.xOffset = this.width/2;
    lbl.yOffset = this.height*82/100    
}
this.NoOfneedles=2;
if (this.NoOfneedles > 1) {
    this.label = [];
    for (i=0;i<this.NoOfneedles;i++) {
        this.label[i]=new label();
        alert("label xOffset:"+this.label[i]+this.label[i].xOffset);
    }
}

brains911 · Accepted Answer · 2012-07-07 22:13:54Z

1

I think this may be the prob:

In your constructor function label() you are setting xOffset and yOffset to 'this' width and 'this' height, but 'this' doesn't have width/height properties so they are undefined.

answered Jul 7, 2012 at 22:13

brains911

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Comments

MaxArt · Accepted Answer · 2012-07-07 22:20:13Z

1

First, there's a problem in you label function:

lbl.xOffset = this.width/2;

Here, this.width is undefined, because this refers to the object you've create with new label(). But then, the xOffset property of the object would equal to NaN. And this line:

lbl.rText;

does nothing.

edited Jul 7, 2012 at 22:20

answered Jul 7, 2012 at 22:07

MaxArt

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Comments

The Alpha · Accepted Answer · 2012-07-07 22:26:23Z

Your label object has no width and height properties and already others said you that but if you just define width and height inside your constructor then it could be written as follows

function Label() {
   var lbl = this;
   lbl.width=window.outerWidth;
   lbl.height=window.outerHeight;
   lbl.precision =1;
   lbl.prefix = '';
   lbl.suffix = '';
   lbl.xOffset = lbl.width/2;
   lbl.yOffset = lbl.height*82/100    
}

this.NoOfneedles=2;
if (this.NoOfneedles > 1){
    this.label = [];
    for (i=0;i<this.NoOfneedles;i++){
        this.label[i]=new Label();
        alert ("label xOffset:"+this.label[i].xOffset);
    }
}

Remember this refers to current object and you are using this.width/2; inside your constructor so this=Label and I've changed the label to Label and outside the constructor/in global scope this refers to default global object window and in the global scope this.someVar and someVar is same because window is the default global object and by default we don't need to use it so we can use document.getElementbyId instrad of window.document.getElementbyId.

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