将给定的数组从顶级分类递归查找子分类，最终构建一个树状数组

[lgwebdream]

/*
 *数组：[{id:1, parentId: 0}, {id:2, parentId:1},{id:3, parentId:1}]
 *输出结果：[{id:1, parentId: 0,children:[{id:2, parentId:1},{id:3, parentId:1}]}]
 *说明：parentId为0 的是根节点
 */

[lgwebdream]

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[523451928]

var arr = [{ id: 1, parentId: 0 }, { id: 2, parentId: 1 }, { id: 3, parentId: 1 }]
function buildTree(arr) {
  const result = []
  const copyArr = [...arr]
  const map = {}
  copyArr.forEach((item) => {
    map[item.id] = item
  })
  for (const key in map) {
    const item = map[key]
    if (item.parentId === 0) {
      result.push(item)
    } else {
      const parent = map[item.parentId]
      parent.children = parent.children || []
      parent.children.push(item)
    }
  }
  return result
}
buildTree(arr)

[AAA611]

代码

function fn(arr) {
  let parents = []
  const len = arr.length

  for (let i = 0; i < len; i++) {
    parents[arr[i].id] = arr[i]
  }

  let parent
  for (let i = 0; i < arr.length; i++) {
    parent = parents[arr[i].parentId]
    if (!parent) continue
    if (parent.children) {
      parent.children.push(arr[i])
    } else {
      parent.children = [arr[i]]
    }
    arr.splice(i, 1)
    i--
  }

  return arr
}