removeDuplicates.js

var removeDuplicates = function(array, getter) {
    var searchArray;
    if (typeof getter === "function"){
        searchArray = array.map(getter);
    } else {
        searchArray = array;
    }
    return array.filter(function(v, k) {
        if (getter){
            v = getter(v);
        }
        return searchArray.indexOf(v) === k;
  });
};

// examples:
removeDuplicates([1,2,3,1,2,3,1,2,3,1,2,3]);
// => [1,2,3]

removeDuplicates("SPRINGTIMEISHERE!".split("")).join("");
// => "SPRINGTMEH!"

removeDuplicates([
    {id:0, value: "value"},
    {id:1, value: "value"},
    {id:1, value: "value"},
    {id:1, value: "value"},
    {id:1, value: "value"},
    {id:1, value: "value"},
    {id:1, value: "value"}], function(v){return v.id})
/* =>
[
    {"id": 0,"value": "value"},
    {"id": 1,"value": "value"}
]
*/