扁平结构的数据数与树形结构的转换

扁平结构转树形结构

方法1:使用数组与对象

  function arrayToTree(arr) {
    const map = {}
    const tree = []
    arr.forEach(item => {
      map[item.id] = { ...item, children: [] }
    })
    arr.forEach(item => {
      if (item.parentId !== 0) {
        map[item.parentId].children.push(map[item.id])
      } else {
        tree.push(map[item.id])
      }
    })
    return tree
  }

方法2:递归

  function buildTree(data, parentId = 0) {
    const tree = []

    data
      .filter(item => item.parentId === parentId)
      .forEach(item => {
        const children = buildTree(data, item.id)

        if (children.length) {
          item.children = children
        }

        tree.push(item)
      })

    return tree
  }

树形结构转扁平结构

递归

function treeToFlat(tree, parentId = 0, result = []) {
  tree.forEach(node => {
    const { id, name, code, children, remark } = node
    result.push({ id, name, code, parentId, remark })

    if (children) {
      treeToFlat(children, id, result)
    }
  })

  return result
}

迭代

function treeToFlat(tree) {
  const stack = [...tree] // 栈数据结构来模拟迭代
  const result = []

  while (stack.length) {
    const node = stack.pop()
    const { id, name, code, parentId, remark, children } = node

    result.push({ id, name, code, parentId, remark })

    if (children) {
      for (let i = children.length - 1; i >= 0; i--) {
        const child = children[i]
        child.parentId = id
        stack.push(child)
      }
    }
  }

  return result
}