如何创建传递对象和键并获取嵌套对象值的函数[重复]

Question

我有一个嵌套对象，我如何拥有传入对象和键并取回值的函数？

示例输入

object = {"a1":{"b1":"{"c1":"d1"}"}}
key = a1/b1/c1
object = {"x1":{"y1":"{"z1":"a1"}"}}
key = x1/y1/z1
value = a1

以下是我尝试过的，但它是错误的

var obj, traverse;

obj = {
  a1: {
    b1: c1,
    b1: d1
  },
  x1: {
    y1: z1,
    y1: a1
  }
};

traverse = function(node, path) {
  var pairs;
  if (!(pairs = _(node).pairs()).length) {
    return [
      {
        keys: path,
        value: node
      }
    ];
  } else {
    return [].concat.apply([], _(pairs).map(function(kv) {
      return traverse(kv[1], path.concat(kv[0]));
    }));
  }
};

console.log(traverse(obj, []));

Answer 1

你可以试试 lodash _.get ，这种访问方式非常棒：

如果找不到路径，你也可以传入一个默认值。

var object = {"a1": { "b1": { "c1": "d1" }}};

console.log("Result at 'a1.b1.c1': ",_.get(object, 'a1.b1.c1'));
console.log("Result at 'a1.b1.nonexistent key': ",_.get(object, 'a1.b1.nonexistent', "default result"));

var object2 = {"x1":{"y1":{"z1":"a1"}}};
console.log("Result at 'x1.y1.z1': ",_.get(object2, 'x1.y1.z1'));

<script src="https://cdnjs.cloudflare.com/ajax/libs/lodash.js/4.17.11/lodash.js"></script>

Answer 2

let obj = {
    a1: {
        b1: {
            nested: true
        },
    },
    x1: {
        y1: 'zl',
    }
};


function getObjectKeys(object, key) {
    // if you want another split key you can change this.
    const keys = key.split('.');
    let obj = object;
    for (let ikey of keys) {
        for (let [objKey, value] of Object.entries(obj)) {
            if(!keys.includes(objKey)) {
                continue;
            }
            obj = value;
        }
    }
    return obj;
}

console.log(getObjectKeys(obj, 'a1.b1.nested'));

console.log(getObjectKeys(obj, 'x1.y1'));
// even if there is another additional key
console.log(getObjectKeys(obj, 'x1.y1.nested'));

不使用任何库， 阅读更多关于Object.entries

Answer 3

如果您可以将键表示为数组，则可以使用 reduce 解决此问题：

const obj = {"x1":{"y1":{"z1":"a1"}}}

const keys = ['x1', 'y1', 'z1']


const value = keys.reduce((acc,key)=>acc[key], obj)// "a1"

作为接受键数组或'x1.y1.z1' 形式的字符串的函数，具有未定义值的后备：

const getValueFromKeys = (obj, keys, defaultValue)=> (Array.isArray(keys)?keys:keys.split('.')).reduce((acc,key)=>acc[key] || defaultValue, obj)