javascript - 从 JSON 中删除元素会留下一个未定义的元素

Question

我有一个 JSON 对象，我需要循环遍历并删除一些元素。但是，在删除元素后，我最终得到了一个未定义的元素，这给我带来了问题，因为我无法使用这个“新 JSON”(我试图在数据表中使用它)

以下是我目前正在做的事情

    function dTable(presId){
  var allregos = '[{"presId": "a09N0000004UbBnIAK","name": "Something","id": "001N000000Mw7knIAB"},{"presId": "a09N0000004UbBnIAK","name": "test catty","id": "001N000000O98IoIAJ"},{"presId": "a09N0000004UbBnIAK","name": "Something","id": "001N000000Mw7knIAB"}]';
  var newJson;
  var regoValue;
  for (var ke in allregos) {
    if (allregos.hasOwnProperty(ke)) {
      regoValue = allregos[ke].presId;
      if(regoValue != presId){
        delete allregos[ke];
      }else{
        //INstead of delete I could maybe create a new JSON by adding the whole node?
        //but I am unable to add the node
        //newJson = newJson.allregos[ke];
      }
    }
  } 

  console.log(allregos);
  console.log(newJson);

  j$('#myRegos').dataTable( {
      "data": newJson,
      "destroy": true,
      "columns": [
          { "title":"Name", "mData": "name", "class": "center" },
      ]
  } );
}

我的控制台日志显示如下内容:

[undefined, undefined, undefined, undefined, undefined, undefined, undefined, undefined, Object { presId="a09N0000004W3YLIA0", name="name 1", id="001N000000Mw7knIAB"}, Object { presId="a09N0000004W3YLIA0", name="Call Centre", id="001N000000MvDaMIAV"}, Object { presId="a09N0000004W3YLIA0", name="Who Is", id="001N000000MvIiaIAF"}]

有办法摆脱不设防的元素吗？

我想到的另一个解决办法是不删除元素，而是将适当的元素添加到新的 JSON 中，但我无法做到这一点。我正在尝试类似的事情:

newJson = newJson.allregos[ke];

Answer 1

这里我们将 allRegos 作为对象数组，因此更好的使用方法是利用标准，而不使用for (var ke in allregos) 然后 if (allregos.hasOwnProperty(ke))我还通过调用 JSON.parse(allregos) 将 json 字符串 转换为 真实 json 数据下面是增强的dTable函数另请注意，我添加了另一个对象 presId='a09N0000004UbBnIAz' 只是为了看看当我们调用 dTable('a09N0000004UbBnIAK');

function dTable(presId){
   allregos = '[{"presId": "a09N0000004UbBnIAK","name": "Something","id": "001N000000Mw7knIAB"}, {"presId": "a09N0000004UbBnIAK","name": "test catty","id": "001N000000O98IoIAJ"}, {"presId": "a09N0000004UbBnIAK","name": "Something","id": "001N000000Mw7knIAB"},{"presId": "a09N0000004UbBnIAz","name": "Something","id": "001N000000Mw7knIAB"}]'; 
   oldJson = allregos; 
   var regoValue;

allregos = JSON.parse(allregos);
oldJson = JSON.parse(oldJson);
newJson = [];



  for( i=0;i<allregos.length;i++){
    regoValue = allregos[i].presId;
    if(regoValue != presId){
        delete allregos[i];
    }else{
        newJson.push(allregos[i]);
    }
  }

  console.log('allregos before:');
  console.log(oldJson);
  console.log('allregos after:')
  console.log(allregos);
  console.log('newJson after:')
  console.log(newJson);

}