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嵌套对象返回未定义的递归函数

javascript

cup_of · 技术社区 · 5 年前

let myObj = [{
    id: 1,
    children: [{
        id: 1.1,
        children: []
      },
      {
        id: 1.2,
        children: []
      }
    ]
  },
  {
    id: 2,
    children: [{
        id: 2.1,
        children: []
      },
      {
        id: 2.2,
        children: []
      }
    ]
  }
]


function addToObj(itemToAdd, parentId, obj) {

  for (let i = 0; i < obj.length; i++) {

    const item = search(obj[i], parentId);

    console.log(item); // undefined

    if (item) {
      item.children = item.children.concat(itemToAdd);
      break;
    }
  }

  function search(obj, id) {
    if (obj.id === id) {
      console.log(obj); // defined (obj with id of 2.1), but returns undefined?
      return obj;
    }

    for (let i = 0; i < obj.children.length; i++) {
      search(obj.children[i], id);
    }
  }

  return obj;
};

const itemToAdd = {
  id: 100,
}

addToObj(itemToAdd, 2.1, myObj);

上面代码段中的函数在对象中循环,查找特定项。如果找到该项,它将在该项的子属性中插入一个对象。

2 回复 | 直到 5 年前

CertainPerformance 5 年前

您需要使用递归函数的返回值 search :如果存在,则返回:

for (let i = 0; i < obj.children.length; i++) {
  const possibleResult = search(obj.children[i], id);
  if (possibleResult) {
    return possibleResult;
  }
}

let myObj = [{
    id: 1,
    children: [{
        id: 1.1,
        children: []
      },
      {
        id: 1.2,
        children: []
      }
    ]
  },
  {
    id: 2,
    children: [{
        id: 2.1,
        children: []
      },
      {
        id: 2.2,
        children: []
      }
    ]
  }
]


function addToObj(itemsToAdd, parentId, obj) {

  for (let i = 0; i < obj.length; i++) {

    const item = search(obj[i], parentId);

    // first log here will be undefined, nothing found
    // second log here will find the object
    console.log('item', item);

    if (item) {
      item.children = item.children.concat(itemsToAdd);
      break;
    }
  }

  function search(obj, id) {
    if (obj.id === id) {
      console.log('obj', obj); // defined (obj with id of 2.1), but returns undefined?
      return obj;
    }

    for (let i = 0; i < obj.children.length; i++) {
      const possibleResult = search(obj.children[i], id);
      if (possibleResult) {
        return possibleResult;
      }
    }
  }

  return obj;
};

const itemToAdd = {
  id: 100,
}

addToObj(itemToAdd, 2.1, myObj);

Maheer Ali 5 年前

如果 (obj.id === id) false
你应该检查一下 obj.children 在循环之前存在。

let myObj = [
  {
    id: 1,
    children: [
    	{
      	id: 1.1,
        children: []
      },
      {
      	id: 1.2,
        children: []
      }
    ]
  },
  {
    id: 2,
    children: [
      {
        id: 2.1,
        children: []
      },
      {
      	id: 2.2,
        children: []
      }
    ]
  }
]

There are two problems in code:

 - List item

function addToObj(itemToAdd, parentId, obj) {

  for (let i=0;i<obj.length;i++) {

    const item = search(obj[i], parentId);

    console.log(item); // undefined

    if (item) {
      item.children = item.children.concat(itemToAdd);
      break;
    }
  }

  function search(obj, id) {
    if (obj.id === id) {
      console.log(obj); // defined (obj with id of 2.1), but returns undefined?
      return obj;
    }
    if(obj.children){
    
    for (let i=0;i<obj.children.length;i++) {
       let x = search(obj.children[i], id);
       if(x) return x;
      }
    }
  }

  return obj;
};

const itemToAdd = {
	id: 100,
}

addToObj(itemToAdd, 2.1, myObj);