Creating a function to log all the hierarchies in the array order by the level

Question

I am trying to create a function which logs all of the hierarchies in the array order by the level.

tried a lot of things but couldn't really figure out.

would like if you can help me out.

const arr = [
  { id: 1, parent_id: 8, level: 2, name: "person1" },
  { id: 2, parent_id: 1, level: 3, name: "person2" },
  { id: 8, parent_id: 0, level: 1, name: "person3" }
];

const func = (arr, level) => {

}

so the hierarchy by giving level 3 will be person2 => person1(since parent_id is 1) => person3(since parent_id is 8)

Thanks for helping !

Answer 1

One way is to change the function so you can call it recursively, then we can call 'ourself' until there are no parents found:

const arr = [
  { id: 1, parent_id: 8, level: 2, name: "person1" },
  { id: 2, parent_id: 1, level: 3, name: "person2" },
  { id: 8, parent_id: 0, level: 1, name: "person3" }
];

const getMatch = (arr, level, isParent = false) => {
  const key = (isParent) ? 'id' : 'level';
  const match = arr.filter(a => a[key] === level)[0];
  if (!match) { return false; }
  
  const parent = getMatch(arr, match.parent_id, true);
  return (parent) ? { ...match, parent } : match; 
}

const res = getMatch(arr, 3);
console.log(res);

{
  "id": 2,
  "parent_id": 1,
  "level": 3,
  "name": "person2",
  "parent": {
    "id": 1,
    "parent_id": 8,
    "level": 2,
    "name": "person1",
    "parent": {
      "id": 8,
      "parent_id": 0,
      "level": 1,
      "name": "person3"
    }
  }
}