1+ <!DOCTYPE html>
2+ < html >
3+ < head >
4+ < meta charset ="utf-8 ">
5+ < title > Set</ title >
6+ < script type ="text/javascript ">
7+ function SetCollection ( ) {
8+ var items = { } ;
9+
10+ //判断集合中是否有该值，有返回true，反之返回false
11+ this . has = function ( value ) {
12+ return items . hasOwnProperty ( value ) ; //return value in items;
13+ } ;
14+
15+ //向集合添加新值
16+ this . add = function ( value ) {
17+ if ( ! this . has ( value ) ) {
18+ items [ value ] = value ;
19+ return true ;
20+ }
21+ return false ;
22+ } ;
23+
24+ //从集合移除一个值
25+ this . remove = function ( value ) {
26+ if ( this . has ( value ) ) {
27+ delete items [ value ] ;
28+ return true ;
29+ }
30+ return false ;
31+ } ;
32+
33+ //移除集合中所有的值
34+ this . clear = function ( ) {
35+ items = { } ;
36+ } ;
37+
38+ //返回集合包含的元素数量
39+ this . size = function ( ) {
40+ var count = 0 ;
41+ for ( var prop in items ) {
42+ if ( items . hasOwnProperty ( prop ) ) {
43+ ++ count ;
44+ }
45+ }
46+ return count ;
47+ //return Object.keys(items).length;简洁的方法返回集合长度
48+ } ;
49+
50+ //返回集合中包含所有值的数组
51+ this . values = function ( ) {
52+ var keys = [ ] ;
53+ for ( var key in items ) {
54+ keys . push ( key ) ;
55+ }
56+ return keys ;
57+ //return Object.keys(items);简洁方法返回集合中所有数值
58+ } ;
59+
60+ //集合并集
61+ this . union = function ( otherSet ) {
62+ var unionSet = new SetCollection ( ) ;
63+
64+ var values = this . values ( ) ;
65+ for ( var i = 0 ; i < values . length ; i ++ ) {
66+ unionSet . add ( values [ i ] ) ;
67+ }
68+
69+ var values = otherSet . values ( ) ;
70+ for ( var i = 0 ; i < values . length ; i ++ ) {
71+ unionSet . add ( values [ i ] ) ;
72+ }
73+
74+ return unionSet ;
75+ } ;
76+
77+ //集合交集
78+ this . intersection = function ( otherSet ) {
79+ var intersectionSet = new SetCollection ( ) ;
80+
81+ var values = this . values ( ) ;
82+ for ( var i = 0 ; i < values . length ; i ++ ) {
83+ if ( otherSet . has ( values [ i ] ) ) {
84+ intersectionSet . add ( values [ i ] ) ;
85+ }
86+ }
87+
88+ return intersectionSet ;
89+ } ;
90+
91+ //集合差集
92+ this . difference = function ( otherSet ) {
93+ var differenceSet = new SetCollection ( ) ;
94+
95+ var values = this . values ( ) ;
96+ for ( var i = 0 ; i < values . length ; i ++ ) {
97+ if ( ! otherSet . has ( values [ i ] ) ) {
98+ differenceSet . add ( values [ i ] ) ;
99+ }
100+ }
101+
102+ return differenceSet ;
103+ } ;
104+
105+ //集合的子集
106+ this . subset = function ( otherSet ) {
107+ if ( this . size ( ) > otherSet . size ( ) ) {
108+ return false ;
109+ } else {
110+ var values = this . values ( ) ;
111+ for ( var i = 0 ; i < values . length ; i ++ ) {
112+ if ( ! otherSet . has ( values [ i ] ) ) {
113+ return false ;
114+ }
115+ }
116+ return true ;
117+ }
118+ } ;
119+ }
120+
121+ var setA = new SetCollection ( ) ;
122+ setA . add ( 1 ) ;
123+ setA . add ( 2 ) ;
124+ setA . add ( 3 ) ;
125+ var setB = new SetCollection ( ) ;
126+ setB . add ( 1 ) ;
127+ setB . add ( 2 ) ;
128+
129+ console . log ( setB . subset ( setA ) )
130+ </ script >
131+ </ head >
132+ < body >
133+
134+ </ body >
135+ </ html >
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