Recursive Array Of Property Values In Array Of Objects

What I need is an array of property values, recursively collected from an array of objects, this is what I mean: const regions = [{ name: 'Europe', subRegions: [{ name: 'Be

Solution 1:

You could reduce the array by looking for arrays and return the codes.

functiongetCodes(array) {
    return array.reduce((r, o) => {
        if ('code'in o) {
            r.push(o.code);
            return r;
        }
        Object.values(o).forEach(v => {
            if (Array.isArray(v)) r.push(...getCodes(v));
        });
        return r;
    }, []);
}

const
    regions = [{ name: 'Europe', subRegions: [{ name: 'BeNeLux', territories: [{ code: 'NL', name: 'Netherlands' }, { code: 'DE', name: 'Germany' }, { code: 'LU', name: 'Luxembourgh' }] }], territories: [{ name: 'United Kingdom', code: 'UK' }, { name: 'AL', code: 'Albania' }, { name: 'ZW', code: 'Switzerland' }] }],
    codes = getCodes(regions);

console.log(codes);

Solution 2:

Assuming that the code properties should always contain the country codes:

It would probably be easier to create one array on the first call, which gets recursively passed down as a parameter, than to create an array for every call and try to combine it later. Then you just need to forEach over the regions and territories and push the code to that array:

const regions = [{
  name: 'Europe',
  subRegions: [{
    name: 'BeNeLux',
    territories: [{
      code: 'NL',
      name: 'Netherlands'
    }, {
      code: 'DE',
      name: 'Germany'
    }, {
      code: 'LU',
      name: 'Luxembourgh'
    }]
  }],
  territories: [{
    name: 'United Kingdom',
    code: 'UK'
  }, {
    code: 'AL',
    name: 'Albania'
  }, {
    code: 'ZW',
    name: 'Switzerland'
  }]
}];

constgetAllTerritoryCodesFromRegions = (regions, allCodes=[]) => {
  regions.forEach(({ territories, subRegions }) => {
    if (territories) {
      territories.forEach(({ code }) => {
        allCodes.push(code);
      });
    }
    if (subRegions) {
      getAllTerritoryCodesFromRegions(subRegions, allCodes);
    }
  });
  return allCodes;
};
console.log(
  getAllTerritoryCodesFromRegions(regions)
);

Solution 3:

You could do it with a recursive method

const getAllTerritoryCodesFromRegions = array => {
    const output = [];

    array.forEach(item => {
        for (const key in item) {
            if (key === 'code') {
                output.push(item[key]);
            } elseif (item.hasOwnProperty(key) && Array.isArray(item[key])) {
                const childOutput = getAllTerritoryCodesFromRegions(item[key]);
                output.push(...childOutput);
            }
        }
    });

    return output;
}

You can find a working example here jsfiddle. However in the dataset from your example you messed up some names and codes.