32-提前声明

<script>
	alert(a)   //function a(){ alert(10) }
	a();      //10
	var a = 3;  

	function a() {
	    alert(10)
	}
	alert(a)  //3
	a = 6;    
	a();     //报错
</script>

==这里第三行 var a=3 会执行；==