最近在做贵州山区希望工程捐赠平台(http://sqph.org/alipay/index.html)的时候,在用json存储的信息里实现联动效果的时候 遇到的问题 无法去除里面重复的项

花了很长时间 实现下面方法 感觉用处不大 

实际上原理很简单 下面是代码

<!DOCTYPE HTML>
<html>
<head>
<title>js去除数组重复项以及js移除json里面的重复项的方法</title>
<meta charset="UTF-8">
<meta name="author" content="yanue" />
<meta name="copyright" content="www.yanue.net" />
</head>
<body>
<script type="text/javascript">
    //去除数组重复
    //var arr = ['a','b','c','a','b','d','b'];
    //去除json数组里面重复
    var arr=[{"cid":1,"county":"小河区"},
    {"cid":1,"county":"小河区"},
    {"cid":2,"county":"南明区"},
    {"cid":1,"county":"小河区"},
    {"cid":1,"county":"小河区"},
    {"cid":3,"county":"乌当区"},
    {"cid":1,"county":"小河区"}];
    var hash = {};
    for ( var i = 0; i < arr.length; i++) {
    //去除数组重复情况
//(hash[arr[i]] == undefined) && (hash[arr[i]]=arr[i]);
//去除json数组里面重复情况
(hash[arr[i]] == undefined) && (hash[arr[i]["cid"]+","+arr[i]["county"]]=arr[i]["cid"]+","+arr[i]["county"]);
}
for(var o in hash){
//alert(o);
cid=o.split(',')[0];
county=o.split(',')[1];
document.write(cid+" "+county+"<br>");
}
</script>
</body>
</html>