javascript在嵌套对象/数组中按值查找

Question

你好，我在函数中返回对象时遇到问题，假设我有一个对象：

var elements = [{
    "fields": null,
    "id_base": "nv_container",
    "icon": "layout",
    "name": "container",
    "is_container": true,
    "elements" : [
        //another elements set here
    ]
}, 
{
    "id_base": "novo_example_elementsec",
    "name": "hello",
    "icon": "edit",
    "view": {}
}];

我想要的是一个可以找到具有特定键和值的对象的函数（在纯 javascript 中），并且我创建了一个函数，但它只是不能正常工作？ ，我的功能：

function findNested(obj, key, value) {
    //Early return
    if (obj[key] === value) {
        console.log( 'before return' ); //until here . its fine
        return obj; //not working
    } else {
        for (var i = 0, len = Object.keys(obj).length; i <= len; i++) {
            if (typeof obj[i] == 'object') {
                this.findNested(obj[i] , key, value);
            }
        }
    }
}

我只是看不出我做错了什么？

谢谢。

Answer 1

在进行递归调用后，您错过了返回。如果在递归后找到对象，您需要继续将该结果冒泡（通过返回它）。正如@scott-marcus 所指出的，您还应该使用i < len（而不是i <= len）。

var elements = [{
    "fields": null,
    "id_base": "nv_container",
    "icon": "layout",
    "name": "container",
    "is_container": true,
    "elements": [
      //another elements set here
    ]
  },
  {
    "id_base": "novo_example_elementsec",
    "name": "hello",
    "icon": "edit",
    "view": {}
  }
];

function findNested(obj, key, value) {
  // Base case
  if (obj[key] === value) {
    return obj;
  } else {
    for (var i = 0, len = Object.keys(obj).length; i < len; i++) {
      if (typeof obj[i] == 'object') {
        var found = this.findNested(obj[i], key, value);
        if (found) {
          // If the object was found in the recursive call, bubble it up.
          return found;
        }
      }
    }
  }
}

console.log(findNested(elements, "icon", "layout")); // returns object
console.log(findNested(elements, "icon", "edit")); // returns object
console.log(findNested(elements, "foo", "bar")); // returns undefined

Answer 2

仅供未来的读者阅读。除了 @user94559 的回答。

1. 更通用的方法是遍历键而不是索引，否则不会找到所有嵌套属性。
2. 在进行递归调用之前检查obj[k] 以忽略空值

var elements = [{
    "fields": null,
    "id_base": "nv_container",
    "icon": "layout",
    "name": "container",
    "is_container": true,
    "elements": [
      {"icon": "nested"}
    ]
  },
  {
    "id_base": "novo_example_elementsec",
    "name": "hello",
    "icon": "edit",
    "view": {}
  }
];

function findNested(obj, key, value) {

  // Base case
  if (obj[key] === value) {
    return obj;
  } else {
    var keys = Object.keys(obj); // add this line to iterate over the keys

    for (var i = 0, len = keys.length; i < len; i++) {
      var k = keys[i]; // use this key for iteration, instead of index "i"

      // add "obj[k] &&" to ignore null values
      if (obj[k] && typeof obj[k] == 'object') {
        var found = findNested(obj[k], key, value);
        if (found) {
          // If the object was found in the recursive call, bubble it up.
          return found;
        }
      }
    }
  }
}

console.log(findNested(elements, "icon", "layout")); // returns object
console.log(findNested(elements, "icon", "edit")); // returns object
console.log(findNested(elements, "foo", "bar")); // returns undefined

// this will work now
console.log(findNested(elements, "icon", "nested")); // returns object