Move key/value in object array to other array by matched item

Question

I have two arrays with objects containing countries and their country code. One of the arrays have the countries in English and also have key with the country's isoCode. It looks like:

[{
 "name": "Denmark",
 "dialCode": "+45",
 "isoCode": "DK",
},
{
 "name": "Germany",
 "dialCode": "+49",
 "isoCode": "DE",
}]

The other array has the country names in Danish and the dialcode but without the isoCode.

[{
 "name": "Danmark",
 "dialCode": "+45",
},
{
 "name": "Tyskland",
 "dialCode": "+49",
}]

Now I want to move/copy the isoCode from the English array to the Danish, matched by the dialCode. But I am a little lost on how to do this.

I have a matching with this

let result = this.dkList.filter(country1 => this.countryList.some(country2 => country2.dialCode === country1.dialCode.replace('00 ', '+').trim()))

My expected result should be

[{
    "name": "Danmark",
    "dialCode": "+45",
    "isoCode": "DK"
  },
  {
    "name": "Tyskland",
    "dialCode": "+49",
    "isoCode": "DE"
  }
]

Are you also able to provide an example of your expected result with the above data? — Nick Parsons
– Nick Parsons, Commented Dec 7, 2021 at 8:47

Nick Parsons · Accepted Answer · 2021-12-07 08:56:13Z

2

The .filter() method is used to remove items from an array, which isn't what you're looking to do here, instead, you're looking to map (ie: transform) your data.

You can first create a Map called isoLookup from your first array that creates keys based. on the dialCode and values based on the isoCode in your array. You can then you this Map to obtain the ISO code using a dialCode. Once you have created the Map lookup, you can use .map() on your second arr2 to map your objects to new objects with an isoCode property, that holds a value obtained from the Map lookup:

const arr1 = [{ "name": "Denmark", "dialCode": "+45", "isoCode": "DK", }, { "name": "Germany", "dialCode": "+49", "isoCode": "DE", }];
const arr2 = [{ "name": "Danmark", "dialCode": "+45", }, { "name": "Tyskland", "dialCode": "+49", }];

const isoLookup = new Map(arr1.map(obj => [obj.dialCode, obj.isoCode]));
const res = arr2.map(obj => ({...obj, isoCode: isoLookup.get(obj.dialCode)}));
console.log(res);

Creating a Map to serve as a lookup allows your code to scale nicely, as apposed to performing the search through arr1 for each iteration of your .map() method.

edited Dec 7, 2021 at 8:56

answered Dec 7, 2021 at 8:50

Nick Parsons

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3 Comments

Morten Hagh Over a year ago

Thanks! Will look into this! I am using filter to remove countries from the english array that can't be found in the danish array, like for example "Antarctica".

Nick Parsons Over a year ago

@MortenHagh ah, got you, I mistook it for code that wasn't working. All good then, .map() for this should be what is needed

Morten Hagh Over a year ago

Got your code to work perfectly with mine! Thank you!

LirysJH · Accepted Answer · 2021-12-07 08:48:45Z

0

Just go through all array elements, compare their dialCodes and copy isoCodes to danish version.

const en = [...]; // array with english data
const den = [...]; // array with danish data

// it will work if en.length = den.length
for (let i = 0; i < en.length; i++) {
  if (den[i].dialCode === en[i].dialCode) { // compare en & den dial codes
    den[i].isoCode = en[i].isoCode;
  }
}

answered Dec 7, 2021 at 8:48

LirysJH

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Comments

NITIN KAR · Accepted Answer · 2021-12-07 09:14:33Z

0

var en = []
var den = []
den.forEach(eni => {
    en.forEach(deni => {
        if (eni.dialcode == deni.dialcode) {
            den.dialcode = en.dialcode
        }
    })
})

now you should have the array in var den

answered Dec 7, 2021 at 9:14

NITIN KAR

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Comments

A1exandr Belan · Accepted Answer · 2021-12-07 12:09:55Z

0

One line solution, if don't mind

const arr1 = [{ "name": "Denmark", "dialCode": "+45", "isoCode": "DK", }, { "name": "Germany", "dialCode": "+49", "isoCode": "DE", }];
const arr2 = [{ "name": "Danmark", "dialCode": "+45", }, { "name": "Tyskland", "dialCode": "+49", }];

result = arr1.map(({ dialCode, isoCode }) => ({ name: arr2.find((o) => dialCode === o.dialCode).name, dialCode, isoCode }));

console.log(result);

answered Dec 7, 2021 at 12:09

A1exandr Belan

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Comments

Yosvel Quintero · Accepted Answer · 2021-12-09 04:58:19Z

0

Because both lists contain dialCode: with Array.prototype.reduce() you can create a hash from arr1 based on the dialCode property and finally get the result out of Array.prototype.map() arr2 list

Code:

const arr1 = [{name: 'Denmark',dialCode: '+45',isoCode: 'DK',},{name: 'Germany',dialCode: '+49',isoCode: 'DE'}]
const arr2 = [{name: ' Danmark',dialCode: '+45',},{name: 'Tyskland',dialCode: '+49'}]

const hash = arr1.reduce((a, c) => ((a[c.dialCode] = c.isoCode), a), {});
const restult = arr2.map(c => ({ ...c, isoCode: hash[c.dialCode] }));

console.log(restult);

edited Dec 9, 2021 at 4:58

answered Dec 7, 2021 at 9:26

Yosvel Quintero

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