Swapping Array elements with Keys

Question

Im trying to swap two array elements in an array that looks like this

[18785:Object, 22260:Object, 22261:Object, 22262:Object, 22263:Object]

I used the following code:

    that.moveMediumDown = function(mediumID){

        var arrKeys = new Array();

        for (key in that.data.medium) {
            arrKeys.push(parseInt(key));
        }

        for (var i = 0; i < arrKeys.length; i++){
            if (arrKeys[i] === parseInt(mediumID)) {

                //swap Medium
                var tmpMedium = that.data.medium[arrKeys[i]];
                that.data.medium[arrKeys[i]] = that.data.medium[arrKeys[i + 1]];
                that.data.medium[arrKeys[i + 1]] = tmpMedium;

                break;
            }
        }

        //build new array with correct ids

        var tmpMediumArray = new Array();

        for (var j = 0; j < arrKeys.length; j++){
            tmpMediumArray[arrKeys[j]] = that.data.medium[arrKeys[j]];
        }
    }

The problem is when I swap the content of the two array elements, the key stays the same. But I need also to swap the key.

So i tried to build a new array with the correct keys but then I get an Array with 22263 elements. Most of them are undefined and only the 5 are correct.

Is there any method to do this without getting such a big array?

Thanks in advance for your help.

score 1 · Answer 1 · answered Feb 05 '14 at 23:01

1

Checkout the array_flip function.

It allows you to swap keys with the elements:

array_flip( {a: 1, b: 1, c: 2} );

becomes

{1: 'b', 2: 'c'}

answered Feb 05 '14 at 23:01

helion3

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Thanks for the answer. But I try to swap elements and not to flip keys and values. Or did I miss something? – NaNO3 Feb 05 '14 at 23:08
Maybe I misunderstand what you mean by "swap elements"? You're trying to swap the keys as `arrKeys` with the array elements, so it's the same. – helion3 Feb 05 '14 at 23:11
I try to swap the element at position 1 in the array with the element at position 3 for example. [18785:Object, 22260:Object, 22261:Object, 22262:Object, 22263:Object] -> [ 22261:Object, 22260:Object, 18785:Object, 22262:Object, 22263:Object] – NaNO3 Feb 05 '14 at 23:14
Why? Are you sorting them? It'd be easier to change their sorting when this array is actually created, but it's possible you don't have access to that. – helion3 Feb 05 '14 at 23:15
So is there no easy way to do this? The problem is more complex than I explained in my question. But I thought there should be an easy solution to swapping two elements. – NaNO3 Feb 05 '14 at 23:19
There are ways to copy and re-assign values from an array but it's an unusually specific task you're trying to solve. If you're trying to sort, it's best to write a custom `.sort` method. – helion3 Feb 05 '14 at 23:22
Hey thanks. That's probably solving my problem. Didn't know one could write custom .sort functions. I'll give it a try. If I succeed I write an answer to my Question. – NaNO3 Feb 05 '14 at 23:28
Ah, yes. Check out: http://stackoverflow.com/questions/979256/sorting-an-array-of-javascript-objects – helion3 Feb 05 '14 at 23:29

Swapping Array elements with Keys

1 Answers1