How to get properties from an Object filtering by an array in Javascript

Question

I have a JS object like this:

const myObj = {
  '$prop1': 1,
  '$prop2': 2,
  '$prop3': 3
};

and an array of object like this:

const myArray = [
  {
    prop1: 'some stuff',
    prop2: 'some other stuff',
    propKey: '$prop1'
  },
        {
    prop1: 'some stuff',
    prop2: 'some other stuff',
    propKey: '$prop2'
  },
        {
    prop1: 'some stuff',
    prop2: 'some other stuff',
    propKey: '$prop5'
  },
];

I am trying to write a function fo filter myObj and only get the fields I can find in myArray.propKey.

this is what I tried so far with no luck:

export const filterVariantContentByColumns = (myObj, myArray) => {
  const objArray = Object.keys(myObj).map(i => myObj[i]);
  return objArray.filter(value => myArray.includes(value.key_name));

  console.log(res);
};

any idea how to do that please?

please add the wanted result.

Nina Scholz
– Nina Scholz

2020-02-16 09:50:41 +00:00
Commented Feb 16, 2020 at 9:50 — Nina Scholz
– Nina Scholz, Commented Feb 16, 2020 at 9:50

Nina Scholz · Accepted Answer · 2020-02-16 09:58:41Z

You could iterate the array and map found properties.

const
    myObj = { $prop1: 1, $prop2: 2, $prop3: 3 },
    myArray = [{ prop1: 'some stuff', prop2: 'some other stuff', propKey: '$prop1' }, { prop1: 'some stuff', prop2: 'some other stuff', propKey: '$prop2' }, { prop1: 'some stuff', prop2: 'some other stuff', propKey: '$prop5' }],
    result = myArray.flatMap(({ propKey }) => propKey in myObj ? myObj[propKey] : []);

console.log(result);

With keys

const
    myObj = { $prop1: 1, $prop2: 2, $prop3: 3 },
    myArray = [{ prop1: 'some stuff', prop2: 'some other stuff', propKey: '$prop1' }, { prop1: 'some stuff', prop2: 'some other stuff', propKey: '$prop2' }, { prop1: 'some stuff', prop2: 'some other stuff', propKey: '$prop5' }],
    result = Object.fromEntries(myArray.flatMap(({ propKey }) => propKey in myObj ? [[propKey, myObj[propKey]]] : []));

console.log(result);

CertainPerformance · Accepted Answer · 2020-02-16 09:59:22Z

0

Turn the myArray into a Set of propKeys first, then filter myObj by whether the key being iterated over is in the Set:

const myObj = {
  '$prop1': 1,
  '$prop2': 2,
  '$prop3': 3
};

const myArray = [
  {
    prop1: 'some stuff',
    prop2: 'some other stuff',
    propKey: '$prop1'
  },
        {
    prop1: 'some stuff',
    prop2: 'some other stuff',
    propKey: '$prop2'
  },
        {
    prop1: 'some stuff',
    prop2: 'some other stuff',
    propKey: '$prop5'
  },
];
const haveKeys = new Set(myArray.map(({ propKey }) => propKey));
const output = Object.entries(myObj)
  .filter(([key]) => haveKeys.has(key))
console.log(output);

edited Feb 16, 2020 at 9:59

answered Feb 16, 2020 at 9:51

CertainPerformance

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1 Comment

CertainPerformance Over a year ago

If you want the entries and not just the keys, then remove the final .map so that you have an array of entries. (if you need an object instead, you can use Object.fromEntries to turn the array of entries into an object)

sfy · Accepted Answer · 2020-02-16 10:13:09Z

0

Another answer.

const myObj = {
  '$prop1': 1,
  '$prop2': 2,
  '$prop3': 3,
  '$prop4': 4
};
const myArray = [
  {
    prop1: 'some stuff',
    prop2: 'some other stuff',
    propKey: '$prop1'
  },
        {
    prop1: 'some stuff',
    prop2: 'some other stuff',
    propKey: '$prop2'
  },
        {
    prop1: 'some stuff',
    prop2: 'some other stuff',
    propKey: '$prop5'
  },
];

let propKeys = myArray.map(ele => ele.propKey)

let obj = Object.keys(myObj).reduce((ret, key) => {
  if (propKeys.indexOf(key) > -1) {
    ret[key] = myObj[key]
  }
  return ret
}, {})
console.log(obj)

answered Feb 16, 2020 at 10:13

sfy

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