Question

例如，如果我们有一个现有对象

const mainObject = {
  title: 'some title',
  topics: {
    topic1: {
      path: '',
      id: 1
    },
    topic2: {
      path: '',
      id: 2
    }
  }
}

，我有一个函数可以获取包含键的数组例如

const arrayOfKeys = ['topics', 'topic1'];

function getObjectByKeys(arrayOfKeys) {
  // problem is length of the array may change
  const myObject = mainObject[arrayOfKeys[0]][arrayOfKeys[1]];
  return myObject;
}

函数应返回

{
      path: '',
      id: 1
}

Answer 1

您可以在此处使用.reduce。用主对象初始化累加器，并在其回调的每次迭代中返回与当前键对应的值。

const mainObject = {
  title: 'some title',
  topics: {
    topic1: {
      path: '',
      id: 1
    },
    topic2: {
      path: '',
      id: 2
    }
  }
}

const arrayOfKeys = ['topics', 'topic1'];

function getObjectByKeys(arrayOfKeys) {
  return arrayOfKeys.reduce((a, el, i, arr) => {
    return a[el] || {};    
  }, mainObject);
}

console.log(getObjectByKeys(arrayOfKeys));

Answer 2

一种可能的解决方案是使用forEach循环。

const mainObject = { title: 'some title', topics: { topic1: { path: '', id: 1 }, topic2: { path: '', id: 2 } } }
const arrayOfKeys = ['topics', 'topic1'];

function getObjectByKeys(arrayOfKeys) {
  let result = Object.assign({}, mainObject);
  arrayOfKeys.forEach(function(key){
    result = result[key];
  });
  return result;
}

console.log(getObjectByKeys(arrayOfKeys));

另一种方法是通过传递reduce函数作为参数来使用callback方法。

const mainObject = { title: 'some title', topics: { topic1: { path: '', id: 1 }, topic2: { path: '', id: 2 } } }
const arrayOfKeys = ['topics', 'topic1'];

getObjectByKeys = (arrayOfKeys) => {
  return arrayOfKeys.reduce((obj, item) => obj[item], mainObject);
}

console.log(getObjectByKeys(arrayOfKeys));

Answer 3

您可以使用reduce()

const mainObject = {
  title: 'some title',
  topics: {
    topic1: {
      path: '',
      id: 1
    },
    topic2: {
      path: '',
      id: 2
    }
  }
};
const arrayOfKeys = ['topics', 'topic1'];

var aa= arrayOfKeys.reduce((carry,value,index)=>{
             return carry[value];
        },mainObject);
        
console.log(aa);

Answer 4

您可以使用递归。

const mainObject = {
  title: 'some title',
  topics: {
    topic1: {
      path: '',
      id: 1
    },
    topic2: {
      path: '',
      id: 2
    },
    topic3: {
      path: 'more depth',
      subtopic: {
        path: '',
        id: 4
      },
      id: 3
    }
  }
}

const arrayOfKeys = ['topics', 'topic3', 'subtopic'];

function getObjectByKeys(arrayOfKeys, currentObj, index = 0) {
  if(index >= arrayOfKeys.length) {
    return currentObj;
  }
  return getObjectByKeys(arrayOfKeys, currentObj[arrayOfKeys[index]], index+1)
}

console.log(getObjectByKeys(arrayOfKeys, mainObject));

Answer 5

您可以按如下所示编辑函数，它将为您提供所需的输出。

function getObjectByKeys(obj, [first, ...rest]) {
  if(rest.length > 0 ) return getObjectByKeys(obj[first], rest) 
  else return obj[first]
}

getObjectByKeys(mainObject, ['topics', 'topic1'])

Answer 6

我会将主题更改为数组，因此查找任何元素变得微不足道。该代码现在几乎可以被人类阅读：“在mainObject的field_name中找到ID为1的条目。”

const mainObject = {
  title: 'some title',
  topics: [
    { id: 1, path: 'first' },
    { id: 2, path: 'second' }
  ]
};
const field_name = 'topics';
const entry_to_find = 1;

const entry = mainObject[ field_name ].find( entry => entry.id === entry_to_find );
console.log( entry );

根据数组中的键构造对象

6 个答案: