Check if key exists in nested object

Question

Before any one sais `Object.keys`, that may not work here. Please read on before voting to close or commenting.

Consider the following object and the value being passed in:

As you can see I have a key, which doesn't exist in this object. But the intention is that the key being passed in might exist some where in this object and if it does I want to return the value of the hide.

So an example would be something like:

// Pseudo code, `object` is the object in the screen shot.
if (object.hasKey('date_of_visit')) {
  return object.find('date_of_visit').hide
}

Everything I have ever found on stack and the webs is "find the key by the value." I do not have the value, I just have a potential key. I have looked at lodash and underscore and a bunch of stack questions but have found nothing.

Any ideas or help would be greatly appreciated. The object nesting should not matter. If I passed in other_cause_of_death I should get back true.

Thoughts?

Edit:

const object = {
  status: {
    cause_of_death: {
      hide: true,
      other_cause_of_death: {
        hide: true
      }
    }
  }
};

Heres a simplified version of the object. Same rules should still apply.

Check this out: gist.github.com/creationix/7473758#file-extract-closure-js — Shubham Agrawal
– Shubham Agrawal, Commented Jun 4, 2019 at 21:57
@philipp if I knew how to do it, in a clean, concise way - trust. I would. Hence the asking for help. — TheWebs
– TheWebs, Commented Jun 4, 2019 at 21:59

slider · Accepted Answer · 2019-06-04 22:10:41Z

1

You can use a recursive approach (DFS) to find the object next to your key. If a non-null object is returned, you can get its hide value:

const data = {
  status: {
    cause_of_death: {
      hide: true,
      other_cause_of_death: {
        hide: true
      }
    },
    date_of_birth: {
      hide: true
    }
  }
};

function findKey(obj, key) {
  if (typeof obj !== 'object') return null;
  if (key in obj) return obj[key];
  for (var k in obj) {
    var found = findKey(obj[k], key);
    if (found) return found;
  }
  return null;
}

console.log(findKey(data, 'date_of_birth'));
console.log(findKey(data, 'cause_of_death'));
console.log(findKey(data, 'other_cause_of_death'));
console.log(findKey(data, 'hello'));

edited Jun 4, 2019 at 22:10

answered Jun 4, 2019 at 22:09

slider

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1 Comment

TheWebs Over a year ago

damn that was fast. I see what you did here, I would have done that in like 9 nested for loops. LOL. Thanks so much man!

Henrik Andersson · Accepted Answer · 2019-06-04 22:10:59Z

0

Since you're working with some structured data this could be a valid approach:

It follows the Immutable.js approach to how getting stuff from immutable maps works.

This will return undefined for an invalid key path.

function getIn(obj, keyPath) {
  return keyPath.reduce((prev, curr) => {
    return Object.keys(prev).length ? prev[curr] : obj[curr];
  }, {});
}

const res = getIn(
    data, ['status', 'cause_of_death', 'other_cause_of_death', 'hide']
);

answered Jun 4, 2019 at 22:10

Henrik Andersson

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1 Comment

TheWebs Over a year ago

As you can see I only pass in one value at a time and @slider's response works much better for my use case.

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