Filter out duplicates from an array

gistfile1.txt

from https://coderwall.com/p/nilaba/simple-pure-javascript-array-unique-method-with-5-lines-of-code

Array.prototype.unique = function() {
  return this.filter(function (value, index, self) { 
    return self.indexOf(value) === index;
  });
}

var arr = ['a', 1, 'a', 2, '1']
arr.unique(); // => ['a', 1, 2, '1']

This solution does NOT require any dependencies like jQuery or prototype.js, and it works for arrays with mixed types!