location.hash history for prototype

location_hash.js

var LocationHash = Class.create({
  currentHash: "",

  initialize: function(proxy) {
    this.proxy = proxy || {
      get: function() {
        return location.hash;
      },

      set: function(value) {
        location.hash = value;
      }
    };
  },

  watch: function(callback) {
    setInterval(function() {
      var pageHash = this.get();
      if (pageHash != this.currentHash) {
        this.currentHash = pageHash;
        callback(pageHash);
      }
    }.bind(this), 100);
  },

  set: function(value) {
    this.currentHash = value;
    this.proxy.set("#" + value);
  },

  get: function() {
    return this.proxy.get().substring(1);
  },
  
  empty: function() {
    return this.get() == "";
  }
});