我需要一个javascript递归函数,当key和json对象传递给这个函数时返回一个值数组

Question

我需要一个javascript递归函数,当key和JavaScript对象传递给这个函数时返回一个值数组.

请注意,嵌套的JavaScript对象具有未知深度.该函数工作正常,但它返回重复.

   function getValuesByKey(object, key) {
    var values = [];
    recursiveFx(object);
    function recursiveFx(object) {
      for (var property in object) {
        if (object.hasOwnProperty(property)) {
          if (typeof object[property] == "object") {
           recursiveFx(object[property]);
          } else {
            //found a property which is not an object
            try {
              if (isDefined(object[key])) {
                console.log('Here is the value that is to be pushed',object[key]);
                values.push(object[key]);
              }
            } catch (e) {

            }
          }
        }
      }
    }
    return values;
  } 

这是isDefined辅助函数

function isDefined(variable) {
    try {
    if (typeof(variable) !== 'undefined') return true;
    } catch (e) {
      return false;
    }
  }

以下是JavaScript对象的示例:

{
      "children": [{
        "id": "5",
        "parentid": "0",
        "text": "Device Guides",
        "index": "1",
        "children": [{
          "id": "10",
          "index": "0",
          "text": "Grandstream GXP-21XX"
        }, {
          "id": "11",
          "index": "1",
          "text": "Polycom Soundstation/Soundpoint"
        }, {
          "id": "23",
          "parentid": "8",
          "index": "2",
          "text": "New Polycom",
          "children": [{
            "id": "5",
            "parentid": "0",
            "text": "Device Guides",
            "index": "1",
            "children": [{
              "id": "10",
              "index": "0",
              "text": "Grandstream GXP-21XX"
            }, {
              "id": "11",
              "index": "1",
              "text": "Polycom Soundstation/Soundpoint"
            }, {
              "id": "23",
              "index": "2",
              "text": "New Polycom"
            }]
          }, {
            "id": "6",
            "parentid": "0",
            "text": "Pre-Sales Evaluation",
            "index": "0",
            "children": []
          }, {
            "id": "7",
            "parentid": "0",
            "text": "Router Setup Guides",
            "index": "2",
            "children": [{
              "id": "9",
              "index": "0",
              "text": "Sonicwall"
            }, {
              "id": "12",
              "index": "1",
              "text": "Cisco"
            }]
          }]
        }, {
          "id": "6",
          "parentid": "0",
          "text": "Pre-Sales Evaluation",
          "index": "0",
          "children": []
        }, {
          "id": "7",
          "parentid": "0",
          "text": "Router Setup Guides",
          "index": "2",
          "children": [{
            "id": "9",
            "index": "0",
            "text": "Sonicwall"
          }, {
            "id": "12",
            "index": "1",
            "text": "Cisco"
          }]
        }]}]};

当我运行这个时,getValuesByKey(jsonObj, 'id');我得到以下数组:

["5", "5", "5", "5", "10", "10", "10", "11", "11", "11", "23", "23", "23", "23", "5", "5", "5", "5", "10", "10", "10", "11", "11", "11", "23", "23", "23", "6", "6", "6", "6", "7", "7", "7", "7", "9", "9", "9", "12", "12", "12", "6", "6", "6", "6", "7", "7", "7", "7", "9", "9", "9", "12", "12", "12"]

请注意,5已返回4次而不是2次

Answer 1

您正在检查key 每次通过对象属性的循环的存在.因此,您获得的值与对象上的属性一样多.所以:

function getValuesByKey(object, key) {
  var values = [];
  recursiveFx(object);
  function recursiveFx(object) {

    if (key in object) values.push(object[key]);
    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^

    for (var property in object) {
      if (object.hasOwnProperty(property)) {
        if (typeof object[property] == "object") {
         recursiveFx(object[property]);
        }
      }
    }
  }
  return values;
} 

替代方案:JSON.stringify与替代品一起使用

无论如何,你可以更容易地做到这一点

function getValuesByKey(object, key) {
  var values = [];
  JSON.stringify(object, function(k, v) { 
    if (k === key) values.push(v);
    return v;
  });
  return values;
}

这使用replacer参数来JSON.stringify截取每个键值对.字符串化的值本身我们不需要扔掉.