Recursively filter out objects that are infinitely nested and return an immutable object

recursiveFilterProp.js

// https://stackblitz.com/edit/recursive-filter-prop?file=index.ts
// perf: https://jsbench.me/8cjrlaine7/1

function flatFilter(nestedProp, compareKey, compareId, arr) {
 return arr.filter(o => {
    const keep = o[compareKey] != compareId;
    if (keep && o[nestedProp]) {
      o[nestedProp] = flatFilter(nestedProp, compareKey, compareId, o[nestedProp]);
    }
    return keep;
  });
}

const ARRAY = [
  {
    id: 1,
    children: [
      {
        id: 2,
        children: [
          {
            id: 3,
          },
          {
            id: 4,
          },
        ],
      },
      {
        id: 5,
        children: [
          {
            id: 3,
          },
        ],
      },
    ],
  },
];

console.log(JSON.stringify(flatFilter('children', 'id', 3, ARRAY), null, 2));

/* result

[
  {
    id: 1,
    children: [
      {
        id: 2,
        children: [
          {
            id: 4,
          },
        ],
      },
      {
        id: 5,
        children: [],
      },
    ],
  },
];

*/

Thanks, really helped me! :)

@Jeremy-Glaus 🙌

I used this in my project. Thanks a lot!!

@ayappaP 🙌

BOA MANO VLW

Thanks, it helped us a lot!

@Sergio-Pedretti 🙌

Hi, thanks for the snippet, helped me a lot. Just in case someone was confused just as I was.
This block causes the original array to be mutated.

 if (keep && o[nestedProp]) {
      o[nestedProp] = flatFilter(nestedProp, compareKey, compareId, o[nestedProp]);
    }

So if you want to make it immutable, you should do something like this:

function flatFilter(nestedProp, predicate, arr) {
  return arr.filter(predicate).map(o => {
      if (o[nestedProp]) {
          return {
              ...o,
              [nestedProp]: flatFilter(nestedProp, predicate, o[nestedProp]),
          };
      } else {
          return o;
      }
  });
}

Then use it like this

const flatFiltered = flatFilter(
        'children',
        child => child.id !== 3,
        ARRAY,
    );
    
 console.log(flatFiltered)