js把普通数据结构变成树型数据结构

普通数据结构 

树型数据结构

调用这个函数的时候一般只需要传data

/**
 * 构造树型结构数据
 * @param {*} data 数据源
 * @param {*} id id字段 默认 'id'
 * @param {*} parentId 父节点字段 默认 'parentId'
 * @param {*} children 孩子节点字段 默认 'children'
 */
export function handleTree(data, id, parentId, children) {
  const config = {
    id: id || 'id',
    parentId: parentId || 'parentId',
    childrenList: children || 'children'
  }

  var childrenListMap = {}
  var nodeIds = {}
  var tree = []

  for (const d of data) {
    const parentId = d[config.parentId]
    if (childrenListMap[parentId] == null) {
      childrenListMap[parentId] = []
    }
    nodeIds[d[config.id]] = d
    childrenListMap[parentId].push(d)
  }

  for (const d of data) {
    const parentId = d[config.parentId]
    if (nodeIds[parentId] == null) {
      tree.push(d)
    }
  }

  for (const t of tree) {
    adaptToChildrenList(t)
  }

  function adaptToChildrenList(o) {
    if (childrenListMap[o[config.id]] !== null) {
      o[config.childrenList] = childrenListMap[o[config.id]]
    }
    if (o[config.childrenList]) {
      for (const c of o[config.childrenList]) {
        adaptToChildrenList(c)
      }
    }
  }
  return tree
}