javascript预编译案例

几个很简单的案例：

demo1：

var a = 1;
function f(){
<pre name="code" class="javascript"><span style="white-space:pre">	</span>var a =2;

alert(a);}f();//2

var a = 1;
function f(a){
	var a =2;
	alert(a);
}
f(); //2

<pre name="code" class="javascript">var a = 1;
function f(){
	a =2;
	alert(a);
}
f(); //2