<script>
			function person(){
				var name='marshal';
				function student(){ //聲明子函數(shù)
					console.log(name);//引用父函數(shù)作用域的變量name
				}
			}
			person();//函數(shù)執(zhí)行，產(chǎn)生閉包
		</script>      

	<script>
			function person(){
				var name='marshal';//js執(zhí)行此行時(shí)，產(chǎn)生閉包
				function student(){ //聲明子函數(shù)
					console.log(name);//引用父函數(shù)作用域的變量name
				}
				student();//內(nèi)部函數(shù)在外部函數(shù)調(diào)用
			}
			person();//函數(shù)執(zhí)行，雖滿足閉包條件，但未產(chǎn)生閉包
		</script>

<script>
			function person(){
				var name='marshal';
				function student(){
					console.log(name);  //該方法代碼內(nèi)為閉包代碼
				}
				return student;
			}
			var p=person();//因創(chuàng)建子函數(shù)對(duì)像，此時(shí)產(chǎn)生第一次閉包,并將子函數(shù)student返回給p，由于p沒(méi)有消失，子函數(shù)引用的變量name，一直在內(nèi)存在存儲(chǔ)，直到將p=null,進(jìn)行回收
			p();//執(zhí)行子函數(shù)的閉包代碼塊，輸出"marhsal"
			p();//第二次執(zhí)行子函數(shù)的閉包代碼塊，輸出"marhsal"
			person();//第二次創(chuàng)建子函數(shù)調(diào)對(duì)象，此時(shí)產(chǎn)生第二次閉包,但不執(zhí)行子函數(shù)student代碼塊      
		</script>

<script>
			function setTimeoutTest(message,time){
				setTimeout(function(){
					alert(message);//嵌套子函數(shù)引用父函數(shù)變量message,產(chǎn)生閉包
				},time);
			}  
			setTimeoutTest('提示信息',1000);
		</script>

<script>
				function count(){
					var i=1;
					function add(){
						i++;
						console.log(i);
					}
					return add;
				}
				var c=count();//生產(chǎn)閉包
				c();//2
				c();//3
				c();//4
		</script>

<script>
			function count(){
				var i=1;
				function add(){
					i++;
					console.log(i);
				}
				return add;
			}
			var c=count();
			c();//2
			c();//3  i的生命周期延長(zhǎng)
	</script>

外部js代碼  out.js  實(shí)現(xiàn)自加與自減
(function count(){
	var i=1;
	function add(){
		i++;
		console.log(i);
	}
	function subtract(){
		i--
		console.log(i);
	}
	window.count={
		add:add,
		subtract:subtract
	}
})();

引用 out.js代碼
<script src=out.js></script>
		<script>
			count.add(); //2
			count.subtract();//1
			count.subtract();//0
		</script>

<script>
     var name="marshal"; //創(chuàng)建全局變量
	 var person={
		 name:"leo",
		 getName:function(){ //返回匿名函數(shù)
			 return function(){  //返回this.name
				return this.name;  //返回字符串
			 }
		 }
	 };
	 alert(person.getName()()); //輸出marshal,內(nèi)部函數(shù)不可能直接訪問(wèn)外部函數(shù)this
	 
</script>

<script>
	     var name="marshal";
			 var person={
				 name:"leo",
				 getName:function(){
					 var that=this;//把this保存到閉包可以訪問(wèn)的另一個(gè)變量中
					 return function(){
						return that.name;
					 }
				 }
			 };
			 alert(person.getName()());//that 指向person，而不是window
	</script>