Deep cloning of objects in javascript

clone.js

/**
 example:

 var params = { fullText: { abc: '123' }, test1: { $in: [1,2,3] }, test2: { $in: ['a','b','c'] } };
 var filter = clone(params);
 delete filter.fullText;
 params.test1.$in[1] = 5;
 params.test2.$in[1] = 'x';
 console.log(params);
 console.log(filter);
*/
var clone = function(obj) {
  if((this instanceof clone) == false) {
    return new clone(obj);
  }

  for(i in obj) {
    if(typeof(obj[i]) == 'object') {
      if(Object.prototype.toString.call(obj[i]) === '[object Array]') {
        this[i] = obj[i].slice();
      } else {
        this[i] = new clone(obj[i]);
      }
    } else {
      this[i] = obj[i];
    }
  }
};