javascript get object keys in array

Question

I have an object similar to the one below:

const obj = {
  "test1": {
    "test12": "val1",
    "test13": {
      "test131": "val1",
      "test132": "val2"
    }
  },
  "test2": "val2"
}

I want to receive the keys as follows:

const keys = [["test1", "test12", "test13", "test131", "test132"], ["test2"]];

What have you tried so far? What is not working? Recursion and Object.keys should help here. — Lux
– Lux, Commented Sep 14, 2022 at 7:03

Nick · Accepted Answer · 2022-09-14 07:20:55Z

2

You can recursively process the entries in the object, collecting keys as you go and flattening the result arrays at all levels other than the top:

const obj = {
  "test1": {
    "test12": "val1",
    "test13": {
      "test131": "val1",
      "test132": "val2"
    }
  },
  "test2": null,
  "test3": {
    "test31": "val3"
  },
  "test4": {
    "test41": [1, 2, 3, 4]
  }
}

const getKeys = (obj, flat = false) => {
  const keys = Object.entries(obj)
    .map(([k, v]) => v instanceof Object && !(v instanceof Array) ? [k, ...getKeys(v, true)] : [k])
  return flat ? keys.flat() : keys
}

const allKeys = getKeys(obj)

console.log(allKeys)

edited Sep 14, 2022 at 7:20

answered Sep 14, 2022 at 7:07

Nick

147k23 gold badges67 silver badges106 bronze badges

Sign up to request clarification or add additional context in comments.

2 Comments

Viktor Luft Over a year ago

This code will run into an error if one of the values is "null" and might not work as expected if one of the values would be an array.

Nick Over a year ago

@ViktorLuft thanks for pointing that out. I've corrected the code to ensure it works correctly in those cases

Viktor Luft · Accepted Answer · 2022-09-14 07:10:55Z

1

Here you go:

const obj = {
  "test1": {
    "test12": "val1",
    "test13": {
      "test131": "val1",
      "test132": "val2"
    }
  },
  "test2": "val2"
};

const mapToKeys = ([key, value]) => {
  if (Object.prototype.toString.call(value) === '[object Object]') {
    return [key, ...getKeys(value)];
  }
  return [key];
};
const getKeys = (o) => Object.entries(o).flatMap(mapToKeys);
const keys = Object.entries(obj).map(mapToKeys);

console.log(keys);

edited Sep 14, 2022 at 7:10

answered Sep 14, 2022 at 7:04

Viktor Luft

9415 silver badges10 bronze badges

Collectives™ on Stack Overflow

javascript get object keys in array

2 Answers 2

2 Comments

Comments

Your Answer

Hot Network Questions

Collectives™ on Stack Overflow

2 Answers 2

2 Comments

Comments

Your Answer

Sign up or log in

Post as a guest

Related