Hash CRUD "class" for JavaScript

hash.js

var HashSearch = new function () {
   var params;

   this.set = function (key, value) {
      params[key] = value;
      this.push();
   };

   this.remove = function (key, value) {
      delete params[key];
      this.push();
   };

   this.get = function (key, value) {
       return params[key];
   };

   this.keyExists = function (key) {
       return params.hasOwnProperty(key);
   };

   this.push= function () {
       var hashBuilder = [], key, value;

       for(key in params) if (params.hasOwnProperty(key)) {
           key = escape(key), value = escape(params[key]); // escape(undefined) == "undefined"
           hashBuilder.push(key + ( (value !== "undefined") ? '=' + value : "" ));
       }

       window.location.hash = hashBuilder.join("&");
   };

   (this.load = function () {
       params = {}
       var hashStr = window.location.hash, hashArray, keyVal
       hashStr = hashStr.substring(1, hashStr.length);
       hashArray = hashStr.split('&');

       for(var i = 0; i < hashArray.length; i++) {
           keyVal = hashArray[i].split('=');
           params[unescape(keyVal[0])] = (typeof keyVal[1] != "undefined") ? unescape(keyVal[1]) : keyVal[1];
       }
   })();
}


/** Usage **

Check if a "hash key" is present:
 HashSearch.keyExists("thekey");

Get the value for a hash key:
 HashSearch.get('thekey');

Set the value for a hash key, and update the URL hash:
 HashSearch.set('thekey', 'hey');

Remove a hash key from the URL:
 HashSearch.remove('thekey');

Reload the hash into the local object:
 HashSearch.load();

Push the current key value set to the URL hash:
 HashSearch.push();

Note that when a key does not exist and you try to get it, it will returned undefined. However, a key could exist with no value -- for example #key=val&novalue where novalue is a key with no value. If you do HashSearch.get("novalue") it would also return undefined. In which case, you should use HashSearch.keyExists("novalue") to verify that it is indeed a key.

**/