js中逻辑或的作用

 1 var config = null;
 2 undefined
 3 var result = config||{};
 4 undefined
 5 result
 6 {}
 7 
 8 var config = undefined;
 9 undefined
10 var result = config || {};
11 undefined
12 result
13 {}
14 
15 var config = '';
16 undefined
17 var result = config||{};
18 undefined
19 result
20 {}
21 
22 var config = 0;
23 undefined
24 var result = config||{};
25 undefined
26 result
27 {}
28 
29 var config = false;
30 undefined
31 var result = config || {};
32 undefined
33 result
34 {}
35 
36 
37 
38 var config = {name:'pine'};//'0'  '1'  true 
39 undefined
40 var result = config||{};
41 undefined
42 result
43 {name: "pine"}
44 
45 
46 var result = config||{};
47 ||在此例中的作用：
48 如果config为null、undefined、''、0、false，则表达式返回{},
49 否则表达式返回config
50 
51 等同于：
52 function  nvl(config){
53     if(config==null||config==undefined||config===''||
54        config===0||config===false){
55         return {}; 
56     }
57     return config;
58 }