JS array recursion for unknown number of objects

Question

I have an Object with nested objects in JS and there's an Object with array that has the same name and can pop up multiple times with different values. I just want to sum the length of each array always going one level deeper till this object is missing.

for example:

0 : {id: 1, importantObject: {id: 1, {importantObject: {id: 1, importantObject:{...},}, somethingElse: 23}, something: 'test'}

1 : {id: 2, importantObject: {id: 24, {importantObject: {id: 55, importantObject:{...},}, somethingElse: 92}, something: 'test'}

and so on..

I've tried to do the following:

const getCount = (a) => {
    let count = 0;
    a.map((b) => {
      if (b.importantObject) {
        count += b.importantObject.length;
        getCount(b.importantObject)
      }
    });
     return count;
  }

However, I don't get the correct count. What am I doing wrong?

Please do not use .map() for simple array iteration. Use .forEach() or a normal loop to do that. — VLAZ
– VLAZ, Commented Mar 21, 2022 at 10:08

Barney · Accepted Answer · 2022-03-21 10:05:39Z

2

when doing recursion you must use recursive call return value

const getCount = (a) => {
  let count = 0;
  for (let b of a) {
    if (b.importantObject) {
      count += b.importantObject.length;
      count += getCount(b.importantObject); // here
    }
  }
  return count;
}

answered Mar 21, 2022 at 10:05

Barney

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1 Comment

Richard Over a year ago

I didn't know that I should also call recursively call the return value. Thanks!

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