|
|
屬性的枚舉:
for/in循環是遍歷對象屬性的方法。如
復制代碼 代碼如下:
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>
Javascript hashtable實現代碼
http://www.jb51.NET/article/20372.htm
JavaScript技術：javascript 哈希表(hashtable)的簡單實現，轉載需保留來源！
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