// 情况一：

// 数据源 var egs = [            {name_1: 'name_1...'},            {name_2: 'name_4...'},            {name_3: 'name_3...'},            {name_0: 'name_0...'},        ].reverse() // 最终想要的数据形式        // {name_1: 'name_1...',        //     children: [        //         {name_2: 'name_2...',        //             children: [        //                 {name_3: 'name_3...'},        //             ]        //         }        //     ]        // }        var result = {}        var key ='children'        s(egs)        function s(arrs) {            arrs.forEach((o, i) => {                console.log('---'+ i + ': ', result)                if (!result[key]) {                    result[key] = [o]                } else {                    o[key] = [result]                    result = o                }             })        }        console.log(result)

// 情况二： // pId 对应父级 id

let arr = [

    { pId: '-1', id: '0', name: '父级1' },

    { pId: '0', id: '1', name: '父级1-1' },

    { pId: '0', id: '2', name: '父级1-2' },

    { pId: '2', id: '21', name: '子级21' },

  ]

  function buildTree (arr) {

    let temp = {}

    let tree = {}

    // 数组转 键值对

    arr.forEach(item => {

      temp[item.id] = item

    })

    let tempKeys = Object.keys(temp)

    tempKeys.forEach(key => {

      // 获取当前项

      let item = temp[key]

      // 当前项 pId

      let _itemPId = item.pId

      // 获取父级项

      let parentItemByPid = temp[_itemPId]

      if (parentItemByPid) {

        if (!parentItemByPid.children) {

          parentItemByPid.children = []

        }

        parentItemByPid.children.push(item)

      } else {

        tree[item.id] = item

      }

    })

    // 对象转数组并返回

    return Object.keys(tree).map(key => tree[key])

  }