JS中的树形数据结构处理

树形数据的一些相关处理方法

// 用于测试的树形数据
const treeData = [
  {
    id: '1',
    name: '测试1',
    pId: '0',
    children: [
      {
        id: '11',
        name: '测试11',
        pId: '1',
        children: [
          {
            id: '111',
            name: '测试111',
            pId: '11',
            children: [
              {
                id: '1111',
                name: '测试1111',
                pId: '111',
              },
              {
                id: '1112',
                name: '测试1112',
                pId: '111',
              }
            ]
          },
          {
            id: '112',
            name: '测试112',
            pId: '11',
            children: [
              {
                id: '1121',
                name: '测试1121',
                pId: '112',
              }
            ]
          },
          {
            id: '113',
            name: '测试113',
            pId: '11',
          },
        ]
      },
      {
        id: '12',
        name: '测试12',
        pId: '1',
        children: [
          {
            id: '121',
            name: '测试121',
            pId: '12',
          }
        ]
      },
      {
        id: '13',
        name: '测试13',
        pId: '1'
      },
      {
        id: '14',
        name: '测试14',
        pId: '1'
      }
    ]
  },
  {
    id: '2',
    name: '测试2',
    pId: '0',
    children: [
      {
        id: '21',
        name: '测试21',
        pId: '2',
        children: [
          {
            id: '211',
            name: '测试211',
            pId: '21',
          },
          {
            id: '212',
            name: '测试212',
            pId: '21',
          }
        ]
      },
      {
        id: '22',
        name: '测试22',
        pId: '2'
      },
    ]
  }
]

1. 递归查找当前节点

方法1：forEach + 回调

function findRecursion (data, key, callback) {
  data.forEach((item, index, arr) => {
    if (item.id === key) {
      return callback(item, index, arr)
    }
    if (item.children) {
      return findRecursion(item.children, key, callback)
    }
  })
}
// 查找 测试1112(1112)
findRecursion(treeData, '1112', (item, index, arr) => {
  console.log('1. 递归查找当前节点:', item, index, arr)
})

方法2：for循环

function getCurrentNode (data, key) {
  let temp = null
  for (let i = 0; i < data.length; i++) {
    if (data[i].id === key) {
      temp = data[i]
      break
    } else if (data[i].children?.length) {
      const o = getCurrentNode(data[i].children, key)
      if (o) {
        temp = o
        break
      }
    }
  }
  return temp
}
const cInfo1 = getCurrentNode(treeData, '1112')
console.log('1. 递归查找当前节点 (2) 1112:', cInfo1)
const cInfo2 = getCurrentNode(treeData, '212')
console.log('1. 递归查找当前节点 (2) 212:', cInfo2)
const cInfo3 = getCurrentNode(treeData, '888')
console.log('1. 递归查找当前节点 (2) 888:', cInfo3)

2. 递归获取当前节点及以下的所有节点id

function getChildId (data, idArr) {
  data.forEach(item => {
    if (item.id) {
      idArr.push(item.id)
    }
    if (item.children) {
      getChildId(item.children, idArr)
    }
  })
  return idArr
}
// 获取 treeData此树以下的所有节点id
const idArr = getChildId(treeData, [])
console.log('2. 获取当前节点及以下的所有节点id', idArr)

3. 递归判断所有后代节点中有无此节点中的一个

function judgeChildrenHad (data, keys) {
  let mark = false
  const fn = (data, keys) => {
    for (let i = 0; i < data.length; i++) {
      if (keys.includes(data[i].id)) {
        mark = true
      } else if (data[i].children?.length) {
        fn(data[i].children, keys)
      }
    }
  }
  fn(data, keys)
  return mark
}
// 判断 treeData后代节点中有无 测试1112(1112)节点
const mark1 = judgeChildrenHad(treeData, ['1112'])
console.log('3. mark1', mark1)
// 判断 treeData后代节点中有无 测试1121(1121)节点
const mark2 = judgeChildrenHad(treeData, ['1121'])
console.log('3. mark2', mark2)
// 判断 treeData后代节点中有无 测试888(888)节点
const mark3 = judgeChildrenHad(treeData, ['888'])
console.log('3. mark3', mark3)

4. 树形数据扁平化

方法1：广度优先遍历

function treeToFlat (data) {
  let queue = []
  let result = []
  queue = queue.concat(JSON.parse(JSON.stringify(data)))
  while (queue.length) {
    const firstItem = queue.shift()
    if (firstItem.children) {
      queue = queue.concat(firstItem.children)
      Reflect.deleteProperty(firstItem, 'children')
    }
    result.push(firstItem)
  }
  return result
}
console.log('4. 树形数据扁平化 方法1：广度优先遍历', treeToFlat(treeData))

方法2：递归

function treeToFlat2(data) {
  const result = []
  data.forEach(item => {
    const obj = {
      name: item.name,
      id: item.id,
      pId: item.pId
    }
    result.push(obj)
    if (item.children?.length) {
      result.push(...treeToFlat2(item.children, item.id))
    }
  })
  return result
}
const res1 = treeToFlat2(treeData)
console.log('4. 树形数据扁平化 方法2：递归', res1)

5. 扁平化数据转树形结构

方法1：Map对象

function flatToTree (data) {
  const result = []
  const itemMap = {}
  for (const item of data) {
    const id = item.id
    const pId = item.pId
    
    if (itemMap[id]) {
      itemMap[id] = {
        ...itemMap[id],
        ...item
      }
    } else {
      itemMap[id] = { ...item }
    }

    const treeItem = itemMap[id]
    
    if (!pId || pId === '0') {
      result.push(treeItem)
    } else {
      if (!itemMap[pId]) {
        itemMap[pId] = {
          children: []
        }
      }
      if (!itemMap[pId].children) {
        itemMap[pId].children = []
      }
      itemMap[pId].children.push(treeItem)
    }
  }
  return result
}
const r = JSON.parse(JSON.stringify(res1))
r.unshift({
  id: '999',
  name: 'yyyyy',
  pId: '1'
})
const res2 = flatToTree(r)
console.log('5. 扁平化数据转树形数据结构 方法1：Map对象', res2)

方法2：递归

function flatToTree2 (data) {
  const result = []
  const fn = (arr, cArr, pId = '0') => {
    for (let i = 0; i< arr.length; i++) {
      const item = { ...arr[i], children: [] }
      if (arr[i].pId === pId) {
        cArr.push(item)
        fn(arr, item.children, arr[i].id)
      }
    }
  }
  fn(data, result)
  return result
}
const r2 = JSON.parse(JSON.stringify(res1))
r2.unshift({
  id: '999',
  name: 'yyyyy',
  pId: '1'
})
console.log('5. 扁平化数据转树形数据结构 方法2：递归', flatToTree2(r2))

6. 查找当前节点的父节点

function getParentNode (data, key) {
  let result = null
  for (let i = 0; i < data.length; i++) {
    if (data[i].children?.length) {
      if (data[i].children.some(item => item.id === key)) {
        result = data[i]
        break
      } else {
        const temp = getParentNode(data[i].children, key)
        if (temp) {
          result = temp
          break
        }
      }
    }
  }
  return result
}
const pResult1 = getParentNode(treeData, '1111')
console.log('6、查找当前节点的父节点 1111: ', pResult1)
const pResult2 = getParentNode(treeData, '212')
console.log('6、查找当前节点的父节点 212: ', pResult2)
const pResult3 = getParentNode(treeData, '888')
console.log('6、查找当前节点的父节点 888: ', pResult3)

7. 查找当前节点的所有直系祖先节点（例：当前节点：1111，所有祖先节点为：111,11,1）

function getAllParentNode (data, key) {
  const arr = []
  const fn = (data, key) => {
    const p = getParentNode(data, key)
    if (p && p.id) {
      arr.push(p)
      fn(data, p.id)
    }
  }
  fn(data, key)
  return arr
}
const pArr1 = getAllParentNode(treeData, '1121')
console.log('7、查找当前节点的所有祖先节点 1121:', pArr1)
const pArr2 = getAllParentNode(treeData, '212')
console.log('7、查找当前节点的所有祖先节点 212:', pArr2)

8. 获取树形数据的最深层级数字

function getDeepRank (data) {
  let deepRank = 0
  const fn = (arr, num = 0) => {
    for (let i = 0; i < arr.length; i++) {
      let rank = num || num + 1
      deepRank = Math.max(deepRank, rank)
      if (arr[i].children?.length) {
        fn(arr[i].children, rank + 1)
      }
    }
  }
  fn(data)
  return deepRank
}
console.log('8. 获取树形数据的最深层级数字:', getDeepRank(treeData))

本文题目：JS中的树形数据结构处理
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