How to get only unique items in a multidimensional array with JavaScript/jquery?

Question

I got for example a multidimensional array items with 2 dimensions. I get this array from a database, but it will fill up to 2600+ objects, but if i could some how unique this it would be around 30 objects. How to solve this?

The set up is: How i get the information:

$.getJSON(url1,function(data1)
{
    for (var i in data1.layers){
        $.each(data1.layers[i].legend, function( a, b ) {
            for(var a in data1.layers[i].legend[a]){
                $.each(data1.layers[i].legend, function( key, val ){
                    items.push({label: val.label, url: "long link" + val.url});
                });
            };
        });     
    };

items[0].label  
items[0].url 
items[1].label    
items[1].url

etc...

I found another stackoverflow page about this in php, but i can't get it to work in JavaScript/JQuery. Stackoverflow php solution

Answer 1

You're making a mistake in pushing them onto an array in the first place. You should be creating an associative array, with the key field the unique aspect.

Answer 2

Use a dictionary to see which item you have already:

var dict = {};

$.getJSON(url1,addToLocalArray);

function addToLocalArray(data1){

  for (var i in data1.layers){

    $.each(data1.layers[i].legend, function( a, b ) {

        for(var a in data1.layers[i].legend[a]){

            $.each(data1.layers[i].legend, function( key, val ){

              if(!dict[val.url+'-'+val.label]){
                // or create some sort of unique hash for each element...
                dict[val.url+'-'+val.label] = 1;

                items.push({label: val.label, url: "long link" + val.url});
              }

            });

        }
    });
  }
}

Answer 3

I would suggest either:

A)Push the Uniqueness filtering logic off to the database. It's much more efficient at this, and won't require exhaustive iteration.

B)Have a key for each unique Item (As vogomatix suggested).