access object variable from method javascript

Question

i have a problem accessing an array within an object method. While the log returns the value perfectly, the following line returns an error that allRect[n] is undefined.

I suppose it has something to do with variable accessibility, but the fact that it can be logged in one line and refuses it's existence in the next one leaves me a bit out of ideas.

Thanks all.

        this.s = Snap('#'+id);
        var allRects = [];

        this.xPos = 0;
        var scale = vizWidth/locationSum(data);         

        ...


        //methods
        this.updateViz = function() {

            apiRequest('datasets', 164, 'json').done(   

                function(data){ 
                    var n = 0;


                    data = locationDataIntoArray(data);


                    for(i = 0; i< allRects.length; i++){
                        console.log(allRects[n]);

                        allRects[n].animate({ width:parseInt(data[i][2]), opacity:evaluateMachine(data[i][0])},3000);
                        n++;
                        allRects[n].animate({ width:parseInt(data[i][3]), opacity:evaluateTech(data[i][1])},3000);
                        n++;                
                    }

                }       
            )
        };

Please clarify the two places where you are trying to access it. — Kevin B, Jan 19 '15 at 16:56
Are you sure you don't have a typo somewhere else in your code, where you are referring to `allRects` as `allRect`? — rwacarter, Jan 19 '15 at 16:56
**`an array within an object method`?** The fact that you want to access a local array of a method, indicates that **it should not be local to begin with** — ilgaar, Jan 19 '15 at 17:32

score 0 · Accepted Answer · answered Jan 19 '15 at 16:56

In this code:

                for(i = 0; i< allRects.length; i++){
                    console.log(allRects[n]);

                    allRects[n].animate({ width:parseInt(data[i][2]), opacity:evaluateMachine(data[i][0])},3000);
                    n++;
                    allRects[n].animate({ width:parseInt(data[i][3]), opacity:evaluateTech(data[i][1])},3000);
                    n++;                
                }

you're incrementing n twice on each iteration. Halfway through the for loop, n will be beyond the end of the array.

The first time through the loop, when i and n are both zero, you'll animate allRects[0]. Then you increment n and animate allRects[1], and then increment n again. Thus, on the second time through the loop, you'll be animating allRects[2] and allRects[3], and so on.

indeed, must have overlooked the obvious since i would have expected an out of bound exception... — onkeldittmeyer, Jan 19 '15 at 17:06
@onkeldittmeyer there's no such thing as an "out-of-bounds" exception in JavaScript. — Pointy, Jan 19 '15 at 17:46

access object variable from method javascript

1 Answers1