javascript中没有像c#,java那样的哈希表(hashtable)的实现。在js中,object属性的实现就是hash表,因此只要在object上封装点方法,简单的使用obejct管理属性的方法就可以实现简单高效的hashtable。
首先简单的介绍关于属性的一些方法:
属性的枚举:
for/in循环是遍历对象属性的方法。如
var obj = { name : 'obj1', age : 20, height : '176cm' } var str = ''; for(var name in obj) { str += name + ':' + obj[name] + ' '; } alert(str);
输出为:name:obj1
age:20
height:176cm
检查属性是否存在:
in运算符可以用来测试一个属性是否存在。
this.containsKey = function ( key ) { return (key in entry); }
删除属性
使用delete运算符来删除一个对象的属性。使用delete删除的属性,for/in将不会枚举该属性,并且in运算符也不会检测到该属性。
delete entry[key]; delete obj.name;
下面是哈希表(hashtable)的js的实现方法:
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(); } }
测试:
<!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>
from:http://www.cnblogs.com/hyl8218/archive/2010/01/18/1650589.html