<script> 
function Map() {
 var struct = function(key, value) {
  this.key = key;
  this.value = value;
 }
 
 var put = function(key, value){
  for (var i = 0; i < this.arr.length; i++) {
   if ( this.arr[i].key === key ) {
    this.arr[i].value = value;
    return;
   }
  }
   this.arr[this.arr.length] = new struct(key, value);
 }
 
 var get = function(key) {
  for (var i = 0; i < this.arr.length; i++) {
   if ( this.arr[i].key === key ) {
     return this.arr[i].value;
   }
  }
  return null;
 }
 
 var remove = function(key) {
  var v;
  for (var i = 0; i < this.arr.length; i++) {
   v = this.arr.pop();
   if ( v.key === key ) {
    continue;
   }
   this.arr.unshift(v);
  }
 }
 
 var size = function() {
  return this.arr.length;
 }
 
 var isEmpty = function() {
  return this.arr.length <= 0;
 } 
 this.arr = new Array();
 this.get = get;
 this.put = put;
 this.remove = remove;
 this.size = size;
 this.isEmpty = isEmpty;
}
</script>
<script>
 var map = new Map();
 map.put("re","redhacker");
 map.put("do","douguoqiang");
 map.put("gq","dougq");
 alert("map的大小为：" + map.size())
 alert("key为re的map中存储的对象为：" + map.get("re"));
 map.remove("re");
 alert("移除key为re的对象后，获取key为re的map中存储的对象为：" + map.get("re"));
 alert("map移除一个元素后的大小为：" + map.size());
 alert("map是否是一个空map:" + map.isEmpty());
</script>