Creating a nested object from nested GET parameters

gistfile1.js

var obj = {};
var param1 = "monkey[foo][bar][test1]";
var param2 = "monkey[foo][foo][test2]";
var keys1 = param1.replace(/\]/g, '').split('[');
var keys2 = param2.replace(/\]/g, '').split('[');


var deserialize = function(obj, keys, value){
  var pointer = obj;
  var index = 0;
  keys.forEach(function(key){ // do not use forEach, not working with IE !!!!
    if((index + 1) == keys.length){
      pointer[key] = value
    }else if(pointer[key] === undefined){
      pointer[key] = {};
    }
    index++;
    pointer = pointer[key];
  });
}

deserialize(obj, keys1, '1');
deserialize(obj, keys2, '2');

var obj2 = { monkey: { foo: { bar: "1", foo: "2" } }};
if ( JSON.stringify(obj)==JSON.stringify(obj2) ){
  console.log("works!");
}else {
  console.log("failed");
}