for-in循环详解-优快云博客

本文链接：https://blog.youkuaiyun.com/iteye_5129/article/details/82677909

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for in循环用法一：循环对象属性
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<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
	</head>
	<body>
		<p id="a"></p>
		<script>
			function ForInDemo1() {  
   				var ret = "";  
  				var obj= {"a" : "Athens" ,   
            	"b" : "Belgrade",   
            	"c" : "Cairo"};    
   				for (var key in obj)  {
     				ret += key + ":\t" + obj[key] + "<br/>";  

   				}
   				document.getElementById('a').innerHTML=ret;
			}  
			ForInDemo1();
		</script>
	</body>
</html>

结果如下图

[img]http://dl2.iteye.com/upload/attachment/0122/3979/e3d39c91-9632-35b4-b9c1-a6c1f8db7a21.png[/img]

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for in循环用法二：数组
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<!DOCTYPE html>
<html>
	<head>
		<meta charset="UTF-8">
		<title></title>
	</head>
	<body>
		<p id="b"></p>
		<script>
			function ForInDemo2() {
   				var ret = "";
    			var arr= new Array("zero","one","two");
   				arr["orange"] = "fruit";
    			arr["carrot"] = "vegetable";
    			for (var key in arr){
        			ret += key + ":\t" + arr[key] + "<br/>";
				}
    			document.getElementById('b').innerHTML=ret;

			}
			ForInDemo2();
		</script>
	</body>
</html>