1 function isEqual(a, b) {
2 //如果a和b本来就全等
3 if (a === b) {
4 //判断是否为0和-0
5 return a !== 0 || 1 / a === 1 / b;
6 }
7 //判断是否为null和undefined
8 if (a == null || b == null) {
9 return a === b;
10 }
11 //接下来判断a和b的数据类型
12 var classNameA=toString.call(a),
13 classNameB=toString.call(b);
14 //var classNameA = typeof(a), (兼容IE的写法)
15 //classNameB = typeof(b);
16 //如果数据类型不相等，则返回false
17 if (classNameA !== classNameB) {
18 return false;
19 }
20 if (a instanceof Date)
21 {
22 classNameA = '[object Date]';
23 }
24
25 //如果数据类型相等，再根据不同数据类型分别判断
26 switch (classNameA) {
27 case '[object RegExp]':
28 case '[object String]':
29 case 'string':
30 //进行字符串转换比较
31 return '' + a === '' + b;
32 case 'number':
33 case '[object Number]':
34 //进行数字转换比较,判断是否为NaN
35 if (+a !== +a) {
36 return +b !== +b;
37 }
38 //判断是否为0或-0
39 return +a === 0 ? 1 / +a === 1 / b : +a === +b;
40 case '[object Date]':
41 case '[object Boolean]':
42 case 'boolean':
43 return +a === +b;
44 }
45 //如果是对象类型
46 if (classNameA == '[object Object]' || classNameA=='object') {
47 //获取a和b的属性长度
48 var propsA = Object.getOwnPropertyNames(a),
49 propsB = Object.getOwnPropertyNames(b);
50 if (propsA.length != propsB.length) {
51 return false;
52 }
53 for (var i = 0; i < propsA.length; i++) {
54 var propName = propsA[i];
55 //如果对应属性对应值不相等，则返回false
56 if (a[propName] !== b[propName]) {
57 return false;
58 }
59 }
60 return true;
61 }
62 //如果是数组类型
63 if (classNameA == '[object Array]') {
64 if (a.toString() == b.toString()) {
65 return true;
66 }
67 return false;
68 }
69 }
