Find branches in nested Object in Javascript

Question

I have tried to find a solution for my problem in the last two hours, which included trying myself, scanning lodash docs as well as SO for any suitable answer, but did not come up with anything remotely working or practical. I would be very grateful for help.

I have an object that can be any depth.

e.g.

{
  "name": "alpha",
  "children": [
    {
      "name": "beta",
      "children": [
        {
          "name": "gamma",
          "children": [
            {
              "name": "delta",
              "children": []
            }
          ]
        }
      ]
    },
    {
      "name": "epsilon",
      "children": [
        {
          "name": "zeta",
          "children": [
            {
              "name": "eta",
              "children": []
            }
          ]
        }
      ]
    }
  ]
}

I am looking for a function which will return the whole branch of this object where there is a matching name (if possible without lodash but if really needed its ok).

Given an input of 'gamma' I expect it to return


{
  "name": "alpha",
  "children": [
    {
      "name": "beta",
      "children": [
        {
          "name": "gamma",
          "children": [
            {
              "name": "delta",
              "children": []
            }
          ]
        }
      ]
    }
  ]
}

Given an input 't' I expect it to return the whole object, since it is included in the names of children in both branches.

Why 'a' input should return whole object? As object is having 'a' inside the name ? — Akhil M
– Akhil M, Commented May 29, 2021 at 15:35
@AkhilM because 'a' is included in the names of children both branches. So yes. So when entering 'z' it should only return the branch where 'zeta' occurs — mchl18
– mchl18, Commented May 29, 2021 at 15:37

A1rPun · Accepted Answer · 2021-05-29 16:30:19Z

1

You can separate this problem into two parts, first let's test if the name is present in the tree:

function hasStr(item, str) {
  return item.name.includes(str) || item.children.some(x => hasStr(x, str));
}

hasStr(item, 'gamma'); // true

You also asked to have a function that returns the passed object and return only a filtered version of the children:

function possibleAnswer(item, str) {
  return {
    name: item.name,
    children: item.children.filter(x => hasStr(x, str)),
  };
}

possibleAnswer(item, 'gamma'); // will return desired object

answered May 29, 2021 at 16:30

A1rPun

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Akhil M · Accepted Answer · 2021-05-29 16:15:16Z

-1

This problem can be solved with recursion as the depth is not know.

getNames = (nameChild, match) => {
     if (nameChild.length < 1) return false;

     if (nameChild.name.includes(match)) return true;

     k =  nameChild.children
                   .filter((child) => 
                         getNames(child, match)) 
     return (k.length > 0) ? k : false; 
}

suppose the object is assign to nameObj variable then

nameObj.children = getNames(nameObj, 'zeta');

this will do the work!

answered May 29, 2021 at 16:15

Akhil M

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