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JS 中的foreach和For in比较

发布时间：2025/3/15 54 豆豆
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使用方式举例如下：

<script type="text/javascript"> var jsonranklist=[{"name":"ts","code":123456,"topscore":2000},{"xlid":"tb","code":123456,"topscore":1500}]; console.log(jsonranklist.length);//使用foreach循环 jsonranklist.forEach(function(e){
　　　　　　　　console.log(e.xlid);
　　　　　　});//使用for in 循环 for (var cindxe in jsonranklist) {//var obj=JSON.stringify(dt); console.log(jsonranklist[cindxe].xlid); } </script>

但是IE7之前的版本并不支持Foreach，所以需要自定义方法：

//Array.forEach implementation for IE support.. //https://developer.mozilla.org/en/JavaScript/Reference/Global_Objects/Array/forEach if (!Array.prototype.forEach) {Array.prototype.forEach = function(callback, thisArg) {var T, k;if (this == null) {throw new TypeError(" this is null or not defined");}var O = Object(this);var len = O.length >>> 0; // Hack to convert O.length to a UInt32if ({}.toString.call(callback) != "[object Function]") {throw new TypeError(callback + " is not a function");}if (thisArg) {T = thisArg;}k = 0;while (k < len) {var kValue;if (k in O) {kValue = O[k];callback.call(T, kValue, k, O);}k++;}}; }

完整参考代码如下：

<!DOCTYPE HTML PUBLIC "-//W3C//DTD HTML 4.0 Transitional//EN"> <HTML> <HEAD> <TITLE> New Document </TITLE> <META NAME="Author" CONTENT="oscar999"> </HEAD><BODY> <script> if (!Array.prototype.forEach) {Array.prototype.forEach = function(callback, thisArg) {var T, k;if (this == null) {throw new TypeError(" this is null or not defined");}var O = Object(this);var len = O.length >>> 0; // Hack to convert O.length to a UInt32if ({}.toString.call(callback) != "[object Function]") {throw new TypeError(callback + " is not a function");}if (thisArg) {T = thisArg;}k = 0;while (k < len) {var kValue;if (k in O) {kValue = O[k];callback.call(T, kValue, k, O);}k++;}}; }var arryAll = []; arryAll.push(1); arryAll.push(2); arryAll.push(3); arryAll.push(4); arryAll.push(5);var arrySpecial = [];arryAll.forEach(function(e){if(e%2==0){arrySpecial.push(e);}else if(e%3==0){arrySpecial.push(e);} })</script> </BODY> </HTML>

参考博客地址：
　　　　http://blog.csdn.net/oscar999/article/details/8671546

转载于:https://www.cnblogs.com/xibei666/p/4513618.html

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