Best way to query back unique attribute values in a javascript array of objects?

What would be the best (or fastest) way to find all the possible values of "foo" in the following example array.

var table = [
    {foo: 0, bar:"htns", stuff:123},
    {foo: 2, bar:"snhn", stuff:156},
    {foo: 5, bar:"trltw", stuff:45},
    {foo: 5, bar:"lrctm", stuff:564},
    //few thousand lines later
    {foo: 2596, bar:"cns", stuff:321},
    {foo: 2597, bar:"gcrl", stuff:741}
];

From stackoverflow

• Loop through the array and put the values in a hash (object). It is a O(n) algorithm.

  var result = {};
  for(var i=0; i<table.length; i++) {
      result[table[i].foo] = 1; //the value can be anything
  }
  
  //now read back the unique values
  for (i in result) {
      if (result.hasOwnProperty(i)) { 
          console.log(i);
      }
  }
  

  Christoph : note that the algorithm won't discern between values with identical string representation, eg 5 and '5'

• This is a typesafe version of Chetan's answer:

  var result = {};
  for(var i = 0; i < table.length; ++i) {
      var value = table[i].foo;
      result[(typeof value) + ' ' + value] = value;
  }
  
  for(id in result) {
      if(result.hasOwnProperty(id)) { 
          console.log(result[id]);
      }
  }
  

  It will still break for objects, though: as long as the toString() method hasn't been overwritten, they all share the string representation '[object Object]'.

  Chetan Sastry : Nice trick. You could also look into http://code.google.com/p/jshashtable/ for a true hashtable implementation in javascript.

  Christoph : @Chetan: I actually have my own implementation lying around: http://mercurial.intuxication.org/hg/js-hacks/raw-file/tip/map.js ; see also http://stackoverflow.com/questions/368280/javascript-hashmap-equivalent/383540#383540