js中逻辑或的作用

 var config = null;
 undefined
 var result = config||{};
 undefined
 result
 {}

 var config = undefined;
 undefined
 var result = config || {};
 undefined
 result
 {}

 var config = '';
 undefined
 var result = config||{};
 undefined
 result
 {}

 var config = 0;
 undefined
 var result = config||{};
 undefined
 result
 {}

 var config = false;
 undefined
 var result = config || {};
 undefined
 result
 {}

 var config = {name:'pine'};//'0'  '1'  true
 undefined
 var result = config||{};
 undefined
 result
 {name: "pine"}

 var result = config||{};
 ||在此例中的作用：
 如果config为null、undefined、''、0、false，则表达式返回{},
 否则表达式返回config

 等同于：
 function  nvl(config){
     if(config==null||config==undefined||config===''||
        config===0||config===false){
         return {};
     }
     return config;
 }