 
var obj = { 
name : 'obj1', 
age : 20, 
height : '176cm' 
} 
var str = ''; 
for(var name in obj) 
{ 
str += name + ':' + obj[name] + '\n'; 
} 
alert(str); 

輸出為：name:obj1
　　age:20
　　height:176cm
檢查屬性是否存在:
in運算符可以用來測試一個屬性是否存在。

復制代碼代碼如下:

 
this.containsKey = function ( key ) 
{ 
return (key in entry); 
} 

刪除屬性
使用delete運算符來刪除一個對象的屬性。使用delete刪除的屬性，for/in將不會枚舉該屬性，并且in運算符也不會檢測到該屬性。
delete entry[key];
delete obj.name;
下面是哈希表(hashtable)的js的實現(xiàn)方法：

復制代碼代碼如下:

 
function HashTable() 
{ 
var size = 0; 
var entry = new Object(); 
this.add = function (key , value) 
{ 
if(!this.containsKey(key)) 
{ 
size ++ ; 
} 
entry[key] = value; 
} 
this.getValue = function (key) 
{ 
return this.containsKey(key) ? entry[key] : null; 
} 
this.remove = function ( key ) 
{ 
if( this.containsKey(key) && ( delete entry[key] ) ) 
{ 
size --; 
} 
} 
this.containsKey = function ( key ) 
{ 
return (key in entry); 
} 
this.containsValue = function ( value ) 
{ 
for(var prop in entry) 
{ 
if(entry[prop] == value) 
{ 
return true; 
} 
} 
return false; 
} 
this.getValues = function () 
{ 
var values = new Array(); 
for(var prop in entry) 
{ 
values.push(entry[prop]); 
} 
return values; 
} 
this.getKeys = function () 
{ 
var keys = new Array(); 
for(var prop in entry) 
{ 
keys.push(prop); 
} 
return keys; 
} 
this.getSize = function () 
{ 
return size; 
} 
this.clear = function () 
{ 
size = 0; 
entry = new Object(); 
} 
} 

測試：
代碼

復制代碼代碼如下:

 
<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd"> 
<html xmlns="http://www.w3.org/1999/xhtml"> 
<head> 
<title>HashTable</title> 
<script type="text/javascript" src="/js/jquery.js"></script> 
<script type="text/javascript" src="/js/HashTable.js"></script> 
<script type="text/javascript"> 
function MyObject(name) 
{ 
this.name = name; 
this.toString = function(){ 
return this.name; 
} 
} 
$(function(){ 
var map = new HashTable(); 
map.add("A","1"); 
map.add("B","2"); 
map.add("A","5"); 
map.add("C","3"); 
map.add("A","4"); 
var arrayKey = new Array("1","2","3","4"); 
var arrayValue = new Array("A","B","C","D"); 
map.add(arrayKey,arrayValue); 
var value = map.getValue(arrayKey); 
var object1 = new MyObject("小4"); 
var object2 = new MyObject("小5"); 
map.add(object1,"小4"); 
map.add(object2,"小5"); 
$('#console').html(map.getKeys().join('|') + '<br>'); 
}) 
</script> 
</head> 
<body> 
<div id="console"></div> 
</body> 
</html> 