一維數(shù)組轉(zhuǎn)成樹結(jié)構，如下所示

let arr = [
    {id: 1, name: '部門1', pid: 0},
    {id: 2, name: '部門2', pid: 1},
    {id: 3, name: '部門3', pid: 1},
    {id: 4, name: '部門4', pid: 3},
    {id: 5, name: '部門5', pid: 4},
]
想要輸出結(jié)果
[
    {
        "id": 1,
        "name": "部門1",
        "pid": 0,
        "children": [
            {
                "id": 2,
                "name": "部門2",
                "pid": 1,
                "children": []
            },
            {
                "id": 3,
                "name": "部門3",
                "pid": 1,
                "children": [
                    // 結(jié)果 ,,,
                ]
            }
        ]
    }
]

1.不考慮性能實現(xiàn)，遞歸遍歷查找

/**
 * 遞歸查找，獲取children
 */
const getChildren = (data, result, pid) => {
  for (const item of data) {
    if (item.pid === pid) {
      const newItem = {...item, children: []};
      result.push(newItem);
      getChildren(data, newItem.children, item.id);
    }
  }
}

/**
* 轉(zhuǎn)換方法
*/
const arrayToTree = (data, pid) => {
  const result = [];
  getChildren(data, result, pid)
  return result;
}

2.不用遞歸，也能搞定

function arrayToTree(items) {
  const result = [];   // 存放結(jié)果集
  const itemMap = {};  // 
    
  // 先轉(zhuǎn)成map存儲
  for (const item of items) {
    itemMap[item.id] = {...item, children: []}
  }
  
  for (const item of items) {
    const id = item.id;
    const pid = item.pid;
    const treeItem =  itemMap[id];
    if (pid === 0) {
      result.push(treeItem);
    } else {
      if (!itemMap[pid]) {
        itemMap[pid] = {
          children: [],
        }
      }
      itemMap[pid].children.push(treeItem)
    }

  }
  return result;
}

3.最優(yōu)性能

function arrayToTree(items) {
  const result = [];   // 存放結(jié)果集
  const itemMap = {};  // 
  for (const item of items) {
    const id = item.id;
    const pid = item.pid;

    if (!itemMap[id]) {
      itemMap[id] = {
        children: [],
      }
    }

    itemMap[id] = {
      ...item,
      children: itemMap[id]['children']
    }

    const treeItem =  itemMap[id];

    if (pid === 0) {
      result.push(treeItem);
    } else {
      if (!itemMap[pid]) {
        itemMap[pid] = {
          children: [],
        }
      }
      itemMap[pid].children.push(treeItem)
    }

  }
  return result;
}

https://juejin.cn/post/6983904373508145189