通过js把一个数组修改成多层嵌套多个数组的几种方法总结

let arr = [
     { date: '2020-01-06', age: '18'},
     { date: '2020-01-06', age: '25'},
     { date: '2020-01-07', age: '34'},
     { date: '2020-01-07', age: '18'},
     { date: '2020-01-07', age: '38'},
     { date: '2020-01-08', age: '26'},
     { date: '2020-01-09', age: '24'}
   ]

let dataArr = [];
    arr.map(mapItem => {
      if (dataArr.length == 0) {
          dataArr.push({ date: mapItem.date, List: [mapItem] })
      } else {
         let res = dataArr.some(item=> {//判断相同日期，有就添加到当前项
          if (item.date == mapItem.date) {
            item.List.push(mapItem)
            return true
          }
        })
        if (!res) {//如果没找相同日期添加一个新对象
          dataArr.push({ date: mapItem.date, List: [mapItem] })
        }
      }
    })

dataArr = [
        {
            date:'2020-01-06',
            List: [
                { date: '2020-01-06', age: '18'},
                { date: '2020-01-06', age: '25'}
            ]
        },
        {
            date:'2020-01-07',
            List: [
                { date: '2020-01-07', age: '34'},
                { date: '2020-01-07', age: '18'},
                { date: '2020-01-07', age: '38'},
            ]
        },
        {
            date:'2020-01-08',
            List: [
                 { date: '2020-01-08', age: '26'},
            ]
        },
        {
            date:'2020-01-09',
            List: [
                { date: '2020-01-09', age: '24' }
            ]
        }
    ]

var userArr = [
  { id: "0001", userName: "laozhang_1" },
  { id: "00010001", userName: "laozhang1" },
  { id: "00010002", userName: "laozhang1" },
  { id: "00010003", userName: "laozhang1" },
  { id: "0002", userName: "laowang" },
  { id: "00020002", userName: "laozhang2" },
  { id: "00020003", userName: "laowang" },
  { id: "00020004", userName: "laowang" },
  { id: "00020005", userName: "laowang" },
  { id: "00020006", userName: "laowang" }
];

let newArr = []
 userArr.forEach(item => {
   if (item.id.length === 4) {
     newArr.push({ ...item, list: [] });
  }
 });
newArr.forEach(item => {
  userArr.forEach(user => {
     if (item.id !== user.id && item.id == user.id.substring(0, 4)) {
      item.list.push(user);
    }
  });
 });
console.log(newArr)

var userArr = [
  { id: "0001", userName: "laozhang_1" },
  { id: "00010001", userName: "laozhang1" },
  { id: "00010002", userName: "laozhang1" },
  { id: "00010003", userName: "laozhang1" },
  { id: "0002", userName: "laowang" },
  { id: "00020002", userName: "laozhang2" },
  { id: "00020003", userName: "laowang" },
  { id: "00020004", userName: "laowang" },
  { id: "00020005", userName: "laowang" },
  { id: "00020006", userName: "laowang" }
];

let newArr = userArr.filter(item => item.id.length === 4)
newArr.forEach(item => {
      item.list = userArr.filter(user => item.id !== user.id && item.id == user.id.substring(0, 4))
    })
    console.log(newArr)

let replies = [
	    { id: 1, content: '1. 真理惟一可靠的标准就是永远自相符合', parent: 0 },
	    { id: 2, content: '2. 我需要三件东西：爱情友谊和图书', parent: 0 },
	    { id: 3, content: '2-1 时间是一切财富中最宝贵的财富', parent: 2 },
	    { id: 4, content: '2-2 我读的书愈多，就愈亲近世界，愈明了生活的意义，愈觉得生活的重要', parent: 2 },
	    { id: 5, content: '2-1-1 任何事物都是在不断变化的', parent: 3 },
	    { id: 6, content: '2-1-2 真正的科学家应当是个幻想家', parent: 3 },
	    { id: 7, content: '3. 难得糊涂，耳不闻人之非，不信谣，不传谣', parent: 0 },
	];
function multidimensionalArray(replies) {
    let data = JSON.parse(JSON.stringify(replies)); 
    data.forEach(reply => {
        let parent = data.find(res => res.id === reply.parent); 
        if (parent) {
            parent.children = parent.children || [];
            parent.children.push(reply); 
        }
    });
    return data;
}
console.log(multidimensionalArray(replies))
  /**一维数组处理成多维数组
   * linearArray 一维数组
   *primary 父级id（父子关联字段）
   * secondary 子级id（父子关联字段）
   */
  multidimensionalArray: function (linearArray, primary, secondary) {
    let data = JSON.parse(JSON.stringify(linearArray));
    data.forEach(item => {
      let parent = data.find(res => res[primary] === item[secondary]);
      if (parent) {
        parent.children = parent.children || [];
        parent.children.push(item);
      }
    });
    return data;
  }