Javascript - Multidimensional Array Sorting - String And Int - Order By Int

Question

After dragging divs in my javascript application... I want to assign a numeric class to all divs, ordered by the position. I've researched a lot, and builded the next... but it just does not work. (Inner HTML does not change)

var ele = document.getElementsByTagName("div");
var i = 0;
var MyDrags = [];

while(ele[i]) {
    if(ele[i].id.substr(0, 4)=="drag") {
        MyDrags["distance"]=parseInt(document.getElementById(ele[i].id).style.top,10);
        MyDrags["id"]=ele[i].id;
    }
    i++;
}
MyDrags.sort(function(a,b) {
    return a.distance - b.distance;
});
i = 0;
while(MyDrags["distance"][i]) {
    document.getElementById(MyDrags["id"][i]).innerHTML=MyDrags["distance"][i];
    i++;
}

I strongly recommend if you're going to do DOM manipulation to use Jquery or some other library. It can get hairy if you're doing anything complicated. — VoronoiPotato
– VoronoiPotato, Commented Jul 31, 2012 at 12:38
Use MyDrags = [] instead of MyDrags = new Array() - it's cleaner and more performant. — chrisfrancis27
– chrisfrancis27, Commented Jul 31, 2012 at 12:41
@ChrisFrancis Thank you, I tested it twice... and new Array() is always the fastest. However, I will change my way of creating Arrays :) — Kenedy
– Kenedy, Commented Jul 31, 2012 at 13:32
@VoronoiPotato In this case it is just a Simple Y Axis drag and drop. Jquery is too complete for the simple thing I want :) — Kenedy
– Kenedy, Commented Jul 31, 2012 at 13:33
Really? Be careful with those results - it's laid out badly (1 - 3 are comparable, and 4 - 6 are comparable). The original version is a better test. — chrisfrancis27
– chrisfrancis27, Commented Jul 31, 2012 at 13:36

epoch · Accepted Answer · 2012-07-31 12:53:57Z

2

This is because you are overwriting the previous values, you need to assign a new object in each iteration, to have your code working, it should look like this:

var ele = document.getElementsByTagName('div');
var i = 0;
var MyDrags = [], dst;

while (ele[i]) {
    if (ele[i].id.substr(0, 4) === 'drag') {
        MyDrags.push({
            distance: parseInt(document.getElementById(ele[i].id).style.top, 10),
            id: ele[i].id
        });
    }
    i++;
}

MyDrags.sort(function(a, b) {
    return a.distance - b.distance;
});

i = 0; 
while(MyDrags[i]) {
    if (dst = MyDrags[i]['distance']) {
        document.getElementById(MyDrags[i]['id']).style.top = dst + 'px';
        document.getElementById(MyDrags[i++]['id']).innerHTML = dst;
    }
}

edited Jul 31, 2012 at 12:53

answered Jul 31, 2012 at 12:34

epoch

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6 Comments

Kenedy Over a year ago

Thank you :D But when I try your code, the browser crashes after dragging the divs (when the sort code is called)... and it does nothing. What does the "dst" mean, when creating the array?

epoch Over a year ago

@Kenedy, i just pointed out the syntax/usage mistakes, i have no context of the rest of your page, would you mind posting a complete jsfiddle?

Kenedy Over a year ago

Yes, of course... thank you! :D I pasted the code from my original HTML, but it does not work in the fiddle. Anyway, this is the original FULL code. URL: jsfiddle.net/S7yVC

Kenedy Over a year ago

Thank you again. Now, the problem is that it still does not show the sorted position. InnerHTML is never updated. If I put an alert in the last while it is never called... and if I put it before the while alert(MyDrags["distance"]); it outputs "Undefined"... strange...

Kenedy Over a year ago

Wow... it works perfectly!... What does the console log do in this case?

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