I have a parent-child array that lookes like this:

const myTestArray = [
    {
        "id": "1",
        "parent": "root"
    },
    {
        "id": "2",
        "parent": "1"
    },
    {
        "id": "3",
        "parent": "1"
    },
    {
        "id": "4",
        "parent": "2"
    },
    {
        "id": "5",
        "parent": "4"
    }
];

From this I have been able to create an nested parent-child json-tree, but now I need another data-structure that looks like this:

const childesArray = {

    "1": ["1", "2", "3", "4", "5"],
    "2": ["2", "4", "5"],
    "3": ["3"],
    "4": ["4", "5"],
    "5": ["5"]
};

For each element in myTestArray I need an array that contains all childes (deep) for that element.

I guess I also here can use reduce on this array, but I'm stucked right now how I can achive this. Anyone that can point me in the right direction? Or have any solution on this?

Br. Rune

CodePudding user response：

There are several ways to achieve this, but I tried to keep it simple. Take a look at this example.

const nesting = {};

myTestArray.forEach((item) => {
  const { parent, id } = item;

  if (!nesting[id]) {
    nesting[id] = [id];
  }

  if (!nesting[parent] && parent !== "root") {
    nesting[parent] = [parent];
  }

  if (parent !== "root") {
    nesting[parent].push(id);
  }
});

console.log(nesting);
//
//   {
//     "1":["1","2","3"],
//     "2":["2","4"],
//     "3":["3"],
//     "4":["4","5"],
//     "5":["5"]
//    } 
//

CodePudding user response：

You could take the JSON object and iterate through it with a ForEach loop. You can then append an element to the index of its parent, and you would end up with a 2-dimensional array such as the one you specified.

var newArr = {}; 
myTestArray.forEach(e => {
    newArr[e.id] = [e.id]; 
    if(e.parent != "root"){
        newArr[e.parent].push(e.id); 
    }
});

would produce

newArr = { '1': [ '1', '2', '3' ],
  '2': [ '2', '4' ],
  '3': [ '3' ],
  '4': [ '4', '5' ],
  '5': [ '5' ] }