jQuery.unique on an array of strings

Question

The description of jQuery.unique() states:

Sorts an array of DOM elements, in place, with the duplicates removed. Note that this only works on arrays

Answer 1

var array=['a','b','c','a'];

    function unique(array)
    {
    var unique_arr=[];
    array.forEach(function(i,e)
    {
    if(unique_arr.indexOf(i)===-1) unique_arr.push(i);
    });
    return unique_arr;
    }
    console.log(unique(array));

Answer 2

It might work on an array strings, etc, but it has not been designed for that use...

Notice that the code for unique() is hiding in Sizzle as uniqueSort: github source

While some of that extra code might seem like it would work on any array, pay close attention to sortOrder as defined here. It does a lot of extra work to put things in "document order" - hence why the documentation states that it should only be used on arrays of DOM elements.