闭包
通俗的讲，函数去访问其他函数的局部变量
function funSome() {
var some = 0;
function funBack() {
console.log(++some);
}
return funBack;
}
var funSomeOne = funSome();
funSomeOne();
funSomeOne();
var funSomeTwo = funSome();
funSomeTwo();
funSomeTwo();
原文：http://www.cnblogs.com/WeWeZhang/p/5786760.html