CODEWITHSUNDEEP
javascript
E1-XP
E1-XP

Reputation: 503

Why does my function always return undefined?

I have written a function to search in a nested object. The problem is that it returns undefined instead of the expected result, that is correctly logged in the console. Whats going on there?

const in1 = [1, 2];
const in2 = [1, 2];

const vDOM = {
  1: {
    ref: in1,
    children: {
      2: {
        ref: in2,
        children: {}
      }
    }
  }
}

const findVDOMNode = function(instance, vDOM) {
  const keys = Object.keys(vDOM);
  const foundKey = keys.find(key => vDOM[key].ref === instance);

  //console.log(foundKey, vDOM, "FK");

  if (!keys.length) {
    console.log('no keys');
    return;
  }
  if (foundKey) {
    console.log('found', vDOM[foundKey]);
    return true; //vDOM[foundKey];
  };

  keys.map(key =>
    findVDOMNode(instance, vDOM[key].children));
}

console.log('res: ', findVDOMNode(in2, vDOM));

Live example: https://stackblitz.com/edit/js-dapzsy

Upvotes: 1

Views: 103

Answers (2)

Nina Scholz
Nina Scholz

Reputation: 386519

Just add return at the end.

return keys.map(key =>
    findVDOMNode(instance, vDOM[key].children));

You could take the values of the object and check it against the instance. If an object is found, check the object as well. For iterating use some with short circuit, if the instance is found.

const
    in1 = [1, 2],
    in2 = [1, 2],
    vDOM = { 1: { ref: in1, children: { 2: { ref: in2, children: {} } } } },
    findVDOMNode = (instance, vDOM) => Object
        .values(vDOM)
        .some(v => v === instance
            || v && typeof v === 'object' && findVDOMNode(instance, v)
        );
  
console.log('res: ', findVDOMNode(in2, vDOM));

Upvotes: 2

parallaxis
parallaxis

Reputation: 196

it looks like you are missing a return statement on the map in the last line of the function

const in1 = [1, 2];
const in2 = [1, 2];

const vDOM = {
  1: {
    ref: in1,
    children: {
      2: {
        ref: in2,
        children: {}
      }
    }
  }
}

const findVDOMNode = function(instance, vDOM) {
  const keys = Object.keys(vDOM);
  const foundKey = keys.find(key => vDOM[key].ref === instance);

  //console.log(foundKey, vDOM, "FK");

  if (!keys.length) {
    console.log('no keys');
    return;
  }
  if (foundKey) {
    console.log('found', vDOM[foundKey]);
    return true; //vDOM[foundKey];
  };
  ///added this return statement
  return keys.map(key =>
    findVDOMNode(instance, vDOM[key].children));
}

console.log('res: ', findVDOMNode(in2, vDOM));

Upvotes: 0

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