在JSON对象中递归搜索属性名称{String}并返回关联的值

Question

我正在尝试在json中搜索属性名称，如果可以找到该属性，则返回它的值，否则返回null。

function returnValueAtProperty(string, exampleObject) {
  for (ch1 in exampleObject) {
    if (ch1 === string) {
      return exampleObject[ch1];
    } else if (typeof(exampleObject[ch1]) == 'object') {
      var ob = exampleObject[ch1]
      for (ch2 in ob) {
        return returnValueAtProperty(string, ob[ch2])
      }
    } else if (Array.isArray(exampleObject[ch1])) {
      var arr = exampleObject[ch1];
      for (var i = 0; i < arr.length;) {
        return returnValueAtProperty(string, arr[i])
      }
    }
  }
}

var exampleObject = {
  "key0": 42,
  "key1": {
    "key2": [{
        "key3": "tag",
        "key4": false
      },
      {
        "key5": null,
        "key6": [3, 141]
      }
    ],
    "key7": null
  }
}

console.log(returnValueAtProperty("key3", exampleObject));

该函数应返回“标签”字符串。或者，如果我调用returnValueAtProperty（“ key6”，exampleObject）之类的函数，则应返回数组

Answer 1

我只是更改了一点代码，我相信如果您在对象验证之前更改数组验证会更好，在javascript中，即使数组类型也可以返回对象，因此数组可能会进入对象 在下面的其他情况下，如果我向您展示我所做的代码更改

for(ch1 in exampleObject){
               if(typeof ch1 === string){
                   return exampleObject[ch1];
               }  else if(Array.isArray(exampleObject[ch1])){
                   var arr = exampleObject[ch1];
                   for(var i=0; i<arr.length;){
                       return returnValueAtProperty(string,arr[i])
                   }
               }
                else if(typeof(exampleObject[ch1])=='object'){
                   var ob = exampleObject[ch1]
                   for(ch2 in ob){
                        return returnValueAtProperty(string, ob[ch2])
                   }
               } 
           }

Answer 2

只要不是null，就可以执行一个循环并返回任何值。

function getValue(object, key) {
    var k, temp;
    if (key in object) return object[key];                // if found return value
    for (k in object) {                                   // iterate keys
        if (object[k] && typeof object[k] === 'object') { // check not null and object
            temp = getValue(object[k], key);              // get sub value, if exists
            if (temp !== null) return temp;               // if not null return value
        }
    }
    return null;
}

var object = { key0: 42, key1: { key2: [{ key3: "tag", key4: false }, { key5: null, key6: [3, 141] }], key7: null } };

console.log(getValue(object, "key3"));
console.log(getValue(object, "key6"));
console.log(getValue(object, "key7"));
console.log(getValue(object, "foo"));

将undefined作为不存在的值，这是一种更好的方法。

function getValue(object, key) {
    var k, temp;
    if (key in object) return object[key];
    for (k in object) {
        if (object[k] && typeof object[k] === 'object') {
            temp = getValue(object[k], key);
            if (temp !== undefined) return temp;
        }
    }
}

var object = { key0: 42, key1: { key2: [{ key3: "tag", key4: false }, { key5: null, key6: [3, 141] }], key7: null } };

console.log(getValue(object, "key3"));
console.log(getValue(object, "key6"));
console.log(getValue(object, "key7"));
console.log(getValue(object, "foo"));

Answer 3

function returnValueAtProperty(string,obj){

  for(var i in obj){

    if(i === string)
      return obj[i]

    else if(obj[i].constructor === Object) {
      const val = returnValueAtProperty(string, obj[i]);
      if(val) return val;
    }

  }

  return null;
}

Answer 4

您在这里犯了一些小错误。

检查：

function returnValueAtProperty(string, exampleObject) {
  for (ch1 in exampleObject) {
    if (ch1 === string) {
      return exampleObject[ch1];
    } else if (typeof(exampleObject[ch1]) == 'object') {
      var ob = exampleObject[ch1];
      return returnValueAtProperty(string, ob);
    } else if (Array.isArray(exampleObject[ch1])) {
      var arr = exampleObject[ch1];
      for (var i = 0; i < arr.length;++i) {
        return returnValueAtProperty(string, arr[i])
      }
    }
  }
}

var exampleObject = {
  "key0": 42,
  "key1": {
    "key2": [{
        "key3": "tag",
        "key4": false
      },
      {
        "key5": null,
        "key6": [3, 141]
      }
    ],
    "key7": null
  }
}

console.log(returnValueAtProperty("key3", exampleObject));