an

[codewycat]

var b = 10;
(function b(){
b = 20;
console.log(b);
})();

如下：
var b = 10;
(function b(){
var b = 20;
console.log(b);
})();
// 20

var b = 10;
(function (){
var b = 20;
console.log(b);
})();
// 20

var b = 10;
(function (){
console.log(b);
})();
// 10