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How to use the flatMap function from lodash

Find comprehensive JavaScript lodash.flatMap code examples handpicked from public code repositorys.

lodash.flatMap is a function provided by the Lodash library that flattens and maps an array of values into a new array.

gulpfile.js

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if (!Array.isArray(nativeDependencies) || nativeDependencies.length === 0) {
    return false;
}
const dependencies = JSON.parse(spawn.sync('npm', ['ls', '--json', '--prod']).stdout.toString());
const jsonProperties = Object.keys(flat.flatten(dependencies));
nativeDependencies = _.flatMap(nativeDependencies, (item) =>
    path.dirname(item.substring(item.indexOf('node_modules') + 'node_modules'.length)).split(path.sep)
)
    .filter((item) => item.length > 0)
    .filter((item) => !item.includes('zeromq') && !item.includes('canvas') && !item.includes('keytar')) // Known native modules

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960

+ 2 other calls in file

album.js

GitHub: thumbsup/thumbsup

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Album.prototype.pickPreviews = function (options) {
  // consider nested albums if there aren't enough photos
  let potential = this.files
  if (potential.length < PREVIEW_COUNT) {
    const nested = _.flatMap(this.albums, 'previews').filter(file => file !== PREVIEW_MISSING)
    potential = potential.concat(nested)
  }
  // choose the previews
  if (!options.albumPreviews || options.albumPreviews === 'first') {

649

+ 4 other calls in file

How does lodash.flatMap work?

lodash.flatMap is a function provided by the Lodash library that flattens and maps an array of values into a new array. When you call lodash.flatMap, you pass in two arguments: the array to be processed and a function that maps each element of the array to a new array. The function should return an array of values for each element of the original array. The lodash.flatMap function then iterates over each element of the input array and applies the mapping function to each element. The resulting arrays are then flattened into a single array, and returned as the result. By default, lodash.flatMap uses a depth of 1 when flattening the resulting array. This means that any arrays returned by the mapping function are flattened by a single level, but any nested arrays within them are left intact. You can change the depth of flattening by passing a second argument to the function. Overall, lodash.flatMap is a convenient way to apply a mapping function to each element of an array and flatten the resulting arrays into a single array. This can be useful for tasks like transforming or filtering data in an array.

validate-assets.js

GitHub: ghedamat/ember-svg-jar

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if (!duplicateIds.length) {
  return;
}

let invalidItems = _.flatMap(duplicateIds, id => _.filter(items, { id }));
return ['Duplicate IDs found:']
  .concat(
    invalidItems.map(
      ({ id, relativePath }) => `ID: "${id}" Relative Path: ${relativePath}`

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index.js

GitHub: rudderlabs/rudder-transformer

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const removeUndefinedValues = (obj) => _.pickBy(obj, isDefined);
const removeNullValues = (obj) => _.pickBy(obj, isNotNull);
const removeUndefinedAndNullValues = (obj) => _.pickBy(obj, isDefinedAndNotNull);
const removeUndefinedAndNullAndEmptyValues = (obj) => _.pickBy(obj, isDefinedAndNotNullAndNotEmpty);
const isBlank = (value) => _.isEmpty(_.toString(value));
const flattenMap = (collection) => _.flatMap(collection, (x) => x);
// ========================================================================
// GENERIC UTLITY
// ========================================================================

+ 15 other calls in file

Ai Example

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const _ = require("lodash");

const data = [
  { id: 1, values: [1, 2, 3] },
  { id: 2, values: [4, 5] },
  { id: 3, values: [6, 7, 8] },
];

const result = _.flatMap(data, (item) =>
  item.values.map((value) => ({ id: item.id, value }))
);

console.log(result);
// Output: [
//   { id: 1, value: 1 },
//   { id: 1, value: 2 },
//   { id: 1, value: 3 },
//   { id: 2, value: 4 },
//   { id: 2, value: 5 },
//   { id: 3, value: 6 },
//   { id: 3, value: 7 },
//   { id: 3, value: 8 }
// ]

In this example, we start with an array of objects data, where each object contains an id property and an array of values. We then call lodash.flatMap on this array, passing in a function that maps each object to an array of { id, value } pairs. The mapping function first calls the map method on the values array of each object, which returns an array of { id, value } pairs. These pairs are then flattened into a single array using lodash.flatMap, and returned as the result. The resulting array contains all { id, value } pairs from each object in the original data array, flattened into a single array.

lodash-contrib.commonjs.js

GitHub: node4good/lodash-contrib

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module.exports.findLastIndex       = _.findLastIndex;
module.exports.findLastKey         = _.findLastKey;
module.exports.first               = _.first;
module.exports.firstExisting       = _.firstExisting;
module.exports.fix                 = _.fix;
module.exports.flatMap             = _.flatMap;
module.exports.flatMapDeep         = _.flatMapDeep;
module.exports.flatMapDepth        = _.flatMapDepth;
module.exports.flatten             = _.flatten;
module.exports.flattenDeep         = _.flattenDeep;

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+ 92 other calls in file

index.js

GitHub: sluukkonen/iiris

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  const lodashCallback = (x) => [x, x]
  const ramdaCallback = (x) => [x, x]
  const nativeCallback = (x) => [x, x]
  return {
    iiris: () => A.flatMap(iirisCallback, array),
    lodash: () => _.flatMap(array, lodashCallback),
    ramda: () => R.chain(ramdaCallback, array),
    native: () => array.flatMap(nativeCallback),
  }
},

liquid.js

GitHub: department-of-veterans-affairs/content-build

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liquid.filters.isAboutItem = (menuArray, path) => {
  const outreachPattern = new RegExp('outreach');
  if (outreachPattern.test(path)) {
    return false;
  }
  const paths = _.flatMap(menuArray, getPath);
  const inMenu = _.indexOf(paths, path);
  return inMenu !== -1;
};

studyRightUpdaters.js

GitHub: UniversityOfHelsinkiCS/oodikone

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const studyRightEducation = getEducation(studyright.education_id)

const personsTermRegistrations = allTermRegistrations.filter(
  registration => registration.study_right_id === studyright.id
)
const termRegistrations = flatMap(personsTermRegistrations, 'term_registrations')

if (!studyRightEducation) return acc

if (isBaMa(studyRightEducation)) {

invoice.js

GitHub: DEFRA/water-abstraction-service

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 * Get the licence numbers for this invoice by inspecting
 * the Licence objects associated with each InvoiceLicence
 * object associated with this invoice
 */
getLicenceNumbers () {
  return flatMap(this.invoiceLicences, invoiceLicence => {
    return invoiceLicence.licence.licenceNumber
  })
}

day23a.js

GitHub: jared-hughes/adventofcode

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    }
  }
}


let perms = _.permutations([0, 1, 2, 3], 4).map((L) =>
  _.flatMap(L.map((e) => [2 * e + 1, 2 * e]))
);


// perms = [[3, 5, 2, 4, 1, 0, 7, 6]];

lodash.js

GitHub: mdmarufsarker/lodash

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console.log(find); // => 4


const findLast = _.findLast([4, 5, 6], n => n % 2 == 0);
console.log(findLast); // => 6


const flatMap = _.flatMap([1, 2], n => [n, n]);
console.log(flatMap); // => [1, 1, 2, 2]


const flatMapDeep = _.flatMapDeep([1, 2], n => [[n, n]]);
console.log(flatMapDeep); // => [1, 1, 2, 2]

+ 15 other calls in file

README.md?plain=1

GitHub: SeregPie/lodash.permutations

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---

Calculate all possible permutations of all possible sizes.

```javascript
let permutations = _.flatMap([2, 4, 6], (v, i, a) => _.permutations(a, i + 1));
// => [[2], [4], [6], [2, 4], [2, 6], [4, 2], [4, 6], [6, 2], [6, 4], [2, 4, 6], [2, 6, 4], [4, 2, 6], [4, 6, 2], [6, 2, 4], [6, 4, 2]]
```

---

+ 3 other calls in file

controller.read.js

GitHub: RedHatInsights/insights-remediations

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    res.json(format.list(remediations, count.length, limit, offset, req.query.sort, req.query.system));
});


async function resolveSystems (remediation) {
    const systems = _.flatMap(remediation.issues, 'systems');
    const ids = _(systems).map('system_id').uniq().value();


    const resolvedSystems = await inventory.getSystemDetailsBatch(ids);

+ 4 other calls in file

util.js

GitHub: WhiteSourceE/bhima

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*   season : 'fall'
* }];
*
* // take the ids from the JSON array
* var filter = take('id');
* var ids = _.flatMap(array, filter); // returns [1, 2, 3];
* var ids = _.map(array, filter); // returns [ [1], [2], [3]];
*
* // take both the id and the season properties from the array
* var filter = take('id', 'season');

util.spec.js

GitHub: WhiteSourceE/bhima

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describe('util.js', () => {
  it('#take() should take values from one key of each object in an array of objects', () => {
    const objects = [{ id : 1 }, { id : 2 }, { id : 3 }];
    const expected = [1, 2, 3];
    const filter = util.take('id');
    const ids = _.flatMap(objects, filter);
    expect(ids).to.deep.equal(expected);
  });


  it('#requireModuleIfExists() should require module if it exists', () => {

validate.js

GitHub: th3rdwave/serverless-rspack

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      func,
    };
  },
);

this.entryFunctions = _.flatMap(entries, (value, key) => {
  const entry = path.relative('.', value);
  const entryFile = _.replace(
    entry,
    new RegExp(`${path.extname(entry)}$`),

index.js

GitHub: wuguokai/gpt_bot

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const getMostRecentVersion = () => {
  const coreMigrations = getMigrations('./packages/bp/dist')
  const modules = fs.readdirSync('./modules')


  const moduleMigrations = _.flatMap(modules, module => getMigrations(`./modules/${module}/dist`))
  const versions = [...coreMigrations, ...moduleMigrations].map(x => x.version).sort(semver.compare)


  return _.last(versions)
}

+ 5 other calls in file

users-permissions.js

GitHub: carboni09/strapi4.0.7-custom

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async getRoutes() {
  const routesMap = {};

  _.forEach(strapi.api, (api, apiName) => {
    const routes = _.flatMap(api.routes, route => {
      if (_.has(route, 'routes')) {
        return route.routes;
      }

+ 5 other calls in file

update.js

GitHub: cym31153/arknights-toolbox

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);
const buildingChars = _.transform(
  langShort === 'zh' ? _.pickBy(buildingData.chars, (v, k) => k.startsWith('char_')) : {},
  (obj, { charId, buffChar }) => {
    const shortId = charId.replace(/^char_/, '');
    obj[shortId] = _.flatMap(buffChar, ({ buffData }) =>
      buffData.map(({ buffId, cond: { phase, level } }) => ({
        id: idStandardization(buffId),
        unlock: `${phase}_${level}`,
      }))

+ 4 other calls in file

parseArguments.js

GitHub: carflynn2009/.dotfiles

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 *  - others are parsed for types
 *  - Returns array of arguments already converted to string with type
 *  @param {*[]} commandArguments
 */
const parseArguments = commandArguments =>
  _.flatMap(_.tail(commandArguments), arg =>
    match(arg)
      .when(
        () => arg.type === 'ObjectExpression',
        () => `${arg.properties[0].key.name}: any`

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