Why my recursive function works only for one level?

Question

I am trying to learn how to cope with the objects and arrays and I saw many ways of iterating objects but recursing doesn't work for me and I don't understand why. What am I doing wrong?

I need to loop through an object and just slightly change something in an array. In my case, it's uppercasing the keys

Here is what I've got for now


const development = {
  port: 8080,
  db: {
    username: "jkdfs",
    password: "dsfsdg",
    name: "kslfjskd",
    test: { test: 12, another: 'value' }
  },
  token_secret: "jfkjdsj",
  hash_rounds: "kjsfkljdfkl"
};

function throughObject(obj) {
  let collection = {};
  for (const key in obj) {
    if (obj.hasOwnProperty(key)) {
      let value = obj[key];

      if (typeof obj[key] !== 'object') {
        collection[key.toUpperCase()] = value;
      } else {
        collection[key.toUpperCase()] = nestedObject(obj[key]);
      }
    }

    function nestedObject(nested) {
      const sub = {};

      for (const k in nested) {
        let v = nested[k];

        if (typeof nested[k] !== 'object') {
          sub[k.toUpperCase()] = v;
        } else {
          nestedObject(v);
        }
      }
      return sub;
    }
  }
  return collection;
}

const r = throughObject(development);
console.log(r);

Also your inner and your outer function do exactly the same thing ... — Jonas Wilms
– Jonas Wilms, Commented Dec 25, 2019 at 13:21
@JonasWilms, yes, I know that they are doing the same stuff. I've added the last one because my recursive didn't work. just was playing around with that — Valary o
– Valary o, Commented Dec 25, 2019 at 13:22
Your nestedObject() function is missing a return or an assignment when it calls itself recursively. — Pointy
– Pointy, Commented Dec 25, 2019 at 13:24

adiga · Accepted Answer · 2019-12-25 13:37:58Z

3

When you're recursively calling the function on an object value, you still need to assign it to the sub object: sub[k.toUpperCase()] = nestedObject(v). Also, you don't need 2 different functions.

const development = {
  port: 8080,
  db: {
    username: "jkdfs",
    password: "dsfsdg",
    name: "kslfjskd",
    test: { test: 12, another: 'value' }
  },
  token_secret: "jfkjdsj",
  hash_rounds: "kjsfkljdfkl"
};

function nestedObject(nested) {
  const sub = {};

  for (const k in nested) {
    const v = nested[k];
    
    if (typeof nested[k] !== 'object')
      sub[k.toUpperCase()] = v;
    else
      sub[k.toUpperCase()] = nestedObject(v); // <- HERE
  }
  return sub;
}

console.log(nestedObject(development))

Here's a shorter version using Object.fromEntries()

const development={port:8080,db:{username:"jkdfs",password:"dsfsdg",name:"kslfjskd",test:{test:12,another:"value"}},token_secret:"jfkjdsj",hash_rounds:"kjsfkljdfkl"};

const convert = o =>
  Object.fromEntries(
    Object.entries(o).map(([k, v]) => 
      [k.toUpperCase(), Object(v) === v ? convert(v) : v]
    )
 )

console.log(convert(development))

edited Dec 25, 2019 at 13:37

answered Dec 25, 2019 at 13:32

adiga

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6 Comments

Valary o Over a year ago

Thanks for your help a lot! But I already tried the first version of your code (not with Object.fromEntries) and it has the same result - only one level of objects is changed. Test stays undefined

Valary o Over a year ago

and I tried to use for in loop because it is much more faster as far as I know. Comparing to Object.values, Object.keys

Valary o Over a year ago

Yes, I can see now that it works in your snippet here but why it doesn't work in my IDE and I've copied and pasted it into codepan and I have an Empty object there?

adiga Over a year ago

@Valaryo check the browser's console. codepen's built-in only shows objects in the first level

Valary o Over a year ago

That's why I already tried to one another function inside it :D but it helped only for one level

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