JS字典

/*字典 Dictionary类*/
function Dictionary() {
  this.add = add;
  this.datastore = new Array();
  this.find = find;
  this.remove = remove;
  this.showAll = showAll;
  this.count = count;
  this.clear = clear;
}
function add(key, value) {
  this.datastore[key] = value;
}
function find(key) {
  return this.datastore[key];
}
function remove(key) {
  delete this.datastore[key];
}
function showAll() {
  var str = "";
  for(var key in this.datastore) {
    str += key + " -> " + this.datastore[key] + "; "
  }
  console.log(str);
}
function count() {
  /*var ss = Object.keys(this.datastore).length;
  console.log("ssss  "+ss);
  return Object.keys(this.datastore).length;*/
  /**/
  var n = 0;
  for(var key in Object.keys(this.datastore)) {
    ++n;
  }
  console.log(n);
  return n;
}
function clear() {
  for(var key in this.datastore) {
    delete this.datastore[key];
  }
}
var pbook = new Dictionary();
pbook.add("Mike", "723");
pbook.add("Jennifer", "987");
pbook.add("Jonathan", "666");
pbook.showAll();//Mike -> 723; Jennifer -> 987; Jonathan -> 666;
pbook.count();//3
pbook.remove("Jennifer");
//pbook.clear();
pbook.showAll();//Mike -> 723; Jonathan -> 666;
pbook.count();//2