javascript hashtable
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
1 var obj = {
2 name : 'obj1',
3 age : 20,
4 height : '176cm'
5 }
6
7 var str = '';
8 for(var name in obj)
9 {
10 str += name + ':' + obj[name] + '\n';
11 }
12 alert(str);
2 name : 'obj1',
3 age : 20,
4 height : '176cm'
5 }
6
7 var str = '';
8 for(var name in obj)
9 {
10 str += name + ':' + obj[name] + '\n';
11 }
12 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);
}
{
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。
1 delete entry[key];
2 delete obj.name;
2 delete obj.name;
下面是哈希表(hashtable)的js的实现方法：
1 function HashTable()
2 {
3 var size = 0;
4 var entry = new Object();
5
6 this.add = function (key , value)
7 {
8 if(!this.containsKey(key))
9 {
10 size ++ ;
11 }
12 entry[key] = value;
13 }
14
15 this.getValue = function (key)
16 {
17 return this.containsKey(key) ? entry[key] : null;
18 }
19
20 this.remove = function ( key )
21 {
22 if( this.containsKey(key) && ( delete entry[key] ) )
23 {
24 size --;
25 }
26 }
27
28 this.containsKey = function ( key )
29 {
30 return (key in entry);
31 }
32
33 this.containsValue = function ( value )
34 {
35 for(var prop in entry)
36 {
37 if(entry[prop] == value)
38 {
39 return true;
40 }
41 }
42 return false;
43 }
44
45 this.getValues = function ()
46 {
47 var values = new Array();
48 for(var prop in entry)
49 {
50 values.push(entry[prop]);
51 }
52 return values;
53 }
54
55 this.getKeys = function ()
56 {
57 var keys = new Array();
58 for(var prop in entry)
59 {
60 keys.push(prop);
61 }
62 return keys;
63 }
64
65 this.getSize = function ()
66 {
67 return size;
68 }
69
70 this.clear = function ()
71 {
72 size = 0;
73 entry = new Object();
74 }
75 }
2 {
3 var size = 0;
4 var entry = new Object();
5
6 this.add = function (key , value)
7 {
8 if(!this.containsKey(key))
9 {
10 size ++ ;
11 }
12 entry[key] = value;
13 }
14
15 this.getValue = function (key)
16 {
17 return this.containsKey(key) ? entry[key] : null;
18 }
19
20 this.remove = function ( key )
21 {
22 if( this.containsKey(key) && ( delete entry[key] ) )
23 {
24 size --;
25 }
26 }
27
28 this.containsKey = function ( key )
29 {
30 return (key in entry);
31 }
32
33 this.containsValue = function ( value )
34 {
35 for(var prop in entry)
36 {
37 if(entry[prop] == value)
38 {
39 return true;
40 }
41 }
42 return false;
43 }
44
45 this.getValues = function ()
46 {
47 var values = new Array();
48 for(var prop in entry)
49 {
50 values.push(entry[prop]);
51 }
52 return values;
53 }
54
55 this.getKeys = function ()
56 {
57 var keys = new Array();
58 for(var prop in entry)
59 {
60 keys.push(prop);
61 }
62 return keys;
63 }
64
65 this.getSize = function ()
66 {
67 return size;
68 }
69
70 this.clear = function ()
71 {
72 size = 0;
73 entry = new Object();
74 }
75 }
测试：
代码
<!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>
<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>
