JS_for循环

/*
 * 增加一层环境
 */
function main(i){
    return i
}
var demo = {}
for(var i=0;i<5;++i){
    ~function(){　　
        var val = main(i);
        demo[i] = function(){
            return val
        }
    }()
    
}
console.log(demo[4]())

/*
 *  while 循环也一样
 */
function main(i){
    return i
}
var demo = {};
var i = 5;
while(i--){
    ~function(){
        var val = main(i);
        demo[i] = function(){
            return val
        }
    }()
    
}
console.log(demo[1]())

/*
 * 经典的闭包
 */
var i = 0, lis = document.getElementsByTagName('li'), val;
while(val = lis[i++]){
    ~function(){
        var temp = i;
        val.onclick = function(){
            console.log(temp)
        }
    }();
}