window. y = "hello";
function func(){
y = "OH, NO!!!";
}
func();
alert(window.y); //#=> display "OH, NO!!!"

var x = "window.x";
function a() {
var x = "a's x";
var b = function() {
var c = function() {
//no var!
x = "c's x:";
};
alert("before c run,the b.x:" + x);
c();
alert("after c run, the b.x:" + x);
};
alert("a.x is:" + x);
b();
alert("after b function runed, the a.x is:" + x);
};
alert("before a run, window.x:" + x);
a();
alert("after a run, window.x:" + x);