Useful Javascript Array prototypes

array.extensions.js

Array.prototype.unique = function() {
    var o = {}, i, l = this.length, r = [];
    for(i=0; i<l;i+=1) o[this[i]] = this[i];
    for(i in o) r.push(o[i]);
    return r;
};

Array.prototype.values_at = function() {
    var o = [], i, l = arguments.length;
    for(i=0; i<l;i+=1) o.push( this[arguments[i]] );
    return o;
};

Array.prototype.flatten = function() {
  b = Array.prototype.concat.apply([], this);
  if (b.length != this.length) b = b.flatten();
  return b;
};