这几道题，你会做吗？

var a =1;
var json = {
    a:10,
    val:function(){
        alert(this.a*=2);
    }
}
json.val();
var b = json.val;
b();
alert("stop-stop")
json.val.call(window);
alert(window.a + json.a);

var a =1;
var json = {
    a:10,
    val:function(){
        alert(a*=2);
    }
}
json.val();
var b = json.val;
b();
alert("stop-stop")
alert(window.a + json.a);

function t1(name){
 if(name) this.name  = name;
}
function t2(name){
 this.name = name;
}
function t3(name){
 this.name = name||"test";
}
t1.prototype.name = "yupeng";
t2.prototype.name = "yupeng";
t2.prototype.name = "yupeng";
alert(new t1().name +new t2().name+new t3().name);

var test = (function(a){
    return function(){
        alert(a*2);
    }
})(2);

test(20);