What is doing $.unique() function in jQuery 1.4.2?

Question

I've got a string with no spaces with ',' and duplicate entries. Why jQuery do not removing this?
var arr = $.unique(data.split(','));

Answer 1

Console says:

> var data = "omg,lol,omg";
> $.unique(data.split(","))
["lol", "omg"]

However it is unreliable because it is meant to be used with DOM nodes. The sorting function that it uses is used to compare DOM nodes and is browser-specific. If you want to de-duplicate an array of strings, then the algorithm used by jQuery.unique can be reused. Sort the array, and remove all consecutive matching elements.

function removeDuplicates(array) {
    array.sort();
    for(var i = 1; i < array.length; i++) {
        if(array[i] == array[i-1]) {
            array.splice(i--, 1);
        }
    }
    return array;
}

Answer 2

$.unique() isn't assured to work on arrays of strings, it has a specific purpose, check the API:

This function only works on plain JavaScript arrays of DOM elements, and is chiefly used internally by jQuery.

Answer 3

I think you're not using the right function for this.

From the jQuery documentation on $.unique:

Note that this only works on arrays of DOM elements, not strings or numbers.

This SO question contains some approaches for a generic array_unique solution.