Json删除元素后长度不变。。。

___紫菜 2015-07-08 02:57:51



 City = [

        { "CityID": 1, "CityName": "深圳", "FirstPY": "S", "IsHot": true, "Sort": 0 },

         { "CityID": 2, "CityName": "广州", "FirstPY": "G", "IsHot": true, "Sort": 0 },

        { "CityID": 3, "CityName": "东莞", "FirstPY": "D", "IsHot": false, "Sort": 0 },

        { "CityID": 4, "CityName": "澳门", "FirstPY": "A", "IsHot": false, "Sort": 0 }

        ];

循环删除了其中某个之后，长度依然保持不变。
应该是逗号引起的，比如我删掉了广州和东莞之后变成下面这样



 City = [

        { "CityID": 1, "CityName": "深圳", "FirstPY": "S", "IsHot": true, "Sort": 0 },

        ,

        ,

        { "CityID": 4, "CityName": "澳门", "FirstPY": "A", "IsHot": false, "Sort": 0 }

        ];

如果我City[1]. CityID 就是undefined 而不是4

不知道有没有什么办法可解决这个问题。。。求解！！！

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娃都会打酱油了 2015-07-09

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数组删除这不是json的问题

香蕉猪 2015-07-09

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循环检查json,,,出现匹配两个逗号的地方就给替换成一个。。。。

hch126163 2015-07-09

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用 splice 删除

forwardNow 2015-07-08

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两种方法：1. 使用splice根据指定索引删元素；2. 清除undefined元素


<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <title>Document</title>
</head>
<body>

<script type="text/javascript">

    // splice(index,howmany)
    // 删除指定index开始的howmany个元素，该方法会维护length值

    var arr = [ "a", "b", "c", "d" ];    

    arr.splice(2, 1); // => ["c"]

    arr; // => ["a", "b", "d"]

</script>

<script>
    
    // 删除数组中的undefined元素
    var arr2 = [ "a", , , null, , undefined, "b" ];

    for ( var i = 0; i < arr2.length; i++ ) { 
        if ( arr2[ i ] === undefined ) {
            arr2.splice( i, 1 );
            i--;
        }
    };
    arr2; // => ["a", null, "b"]

</script>

</body>
</html>

Braska 2015-07-08

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<script>
	var City = [
        { "CityID": 1, "CityName": "深圳", "FirstPY": "S", "IsHot": true, "Sort": 0 },
         { "CityID": 2, "CityName": "广州", "FirstPY": "G", "IsHot": true, "Sort": 0 },
        { "CityID": 3, "CityName": "东莞", "FirstPY": "D", "IsHot": false, "Sort": 0 },
        { "CityID": 4, "CityName": "澳门", "FirstPY": "A", "IsHot": false, "Sort": 0 }
        ];
		City.splice(1,2); //开始位置,删除个数
		alert(City[1].CityID);//弹出4
</script>