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How to use the map function from async

Find comprehensive JavaScript async.map code examples handpicked from public code repositorys.

Async.map is a JavaScript function that applies a given function to each item in an array, and returns an array of the results.

serialport.js

GitHub: guritnoadis/Serial-Port-Node-JS-MySQL

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    factory.emit('error', err);
  }
  return;
}

async.map(files, function (file, callback) {
  var fileName = path.join(dirName, file);
  fs.readlink(fileName, function (err, link) {
    if (err) {
      if (callback) {

unimail-office365.js

GitHub: Salesflare/unimail

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    paramsArray.push(params);
}

let nextPageToken = null;

return Async.map(paramsArray, (callParams, callback) => {

    // Get a big part of the uri. a callback is needed, since a call to the graph API might be needed.
    uri = this._getUri(callParams);

+ 2 other calls in file

How does async.map work?

Async.map works by iterating over each item in an array, and applying a given function to each item. The function takes two arguments: the current item in the array, and a callback function that will be called once the function has completed. The callback function takes two arguments: an error object (if an error occurred), and the result of the function. Async.map then collects the results of each function call into an array, and returns this array once all functions have completed. This allows developers to apply a specific function to each item in an array and collect the results, which can be useful in situations where it is necessary to process large amounts of data in a parallelized and asynchronous way. By providing a convenient and reliable way to perform these tasks, Async.map can help to simplify and streamline complex data processing tasks.

jquery.reading-helper.js

GitHub: megumiimai/jquery-kanji-reading-helper

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 * @param {Function} [callback] - A callback which is called when all `iteratee`
 * functions have finished, or an error occurs. Results is an Array of the
 * transformed items from the `coll`. Invoked with (err, results).
 * @example
 *
 * async.map(['file1','file2','file3'], fs.stat, function(err, results) {
 *     // results is now an array of stats for each file
 * });
 */
var map = doParallel(_asyncMap);

+ 7 other calls in file

index.js

GitHub: davidmerfield/Blot

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// Builds any templates inside the directory
function buildAll(directory, options, callback) {
  var dirs = templateDirectories(directory);


  async.map(dirs, async.reflect(build), function (err, results) {
    results.forEach(function (result, i) {
      if (result.error) {
        if (!options.watch) {
          return callback(result.error);

Ai Example

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const async = require("async");

// Define an array of numbers
const numbers = [1, 2, 3, 4, 5];

// Define a function to apply to each number
const multiplyByTwo = (number, callback) => {
  const result = number * 2;
  callback(null, result);
};

// Apply the function to each number in the array
async.map(numbers, multiplyByTwo, (error, results) => {
  if (error) {
    console.error(error);
    return;
  }

  // Output the results to the console
  console.log(`Original array: ${numbers}`);
  console.log(`Results: ${results}`);
});

In this example, we use async.map() to apply a function (multiplyByTwo) to each item in an array (numbers) and collect the results in a new array. The function multiplyByTwo takes each number in the array and multiplies it by 2, returning the result to the callback function. Async.map applies this function to each item in the array and collects the results in a new array, which is passed to the final callback function. We output both the original array and the results to the console. In this case, the original array is [1, 2, 3, 4, 5], and the results are [2, 4, 6, 8, 10], which are the original numbers multiplied by 2.

index.js

GitHub: abcsFrederick/SAIP

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    if (err) {
        callback(err);
        return;
    }

    async.map(paths.map(function(p) { return path + '/' + p }), directorySize, function(err, sizes) {
        size += sizes.reduce(function(a, b) { return a + b }, 0);
        callback(err, size);
    });
})

create.js

GitHub: OneDev0411/Node-Backend

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  room_type: 'Group',
  owner: user,
  title: override.title || undefined
}

async.map(users, (r, cb) => {
  async.auto({
    room_id: cb => {
      create(room).nodeify(cb)
    },

create.js

GitHub: OneDev0411/Node-Backend

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  source: 'MLS',
  source_url: 'https://mls.org',
  notification: 'Share'
}

async.map(
  user.actions,
  (r, cb) => {
    async.auto(
      {

+ 5 other calls in file

index.js

GitHub: OneDev0411/Node-Backend

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  Task.getAll(tasks).nodeify(cb)
}

const getRevisions = (cb, results) => {
  async.map(results.tasks, (task, cb) => {
    getRevision(results.deal, results.user, task, cb)
  }, cb)
}

+ 5 other calls in file

user.js

GitHub: OneDev0411/Node-Backend

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async.auto({
  agent: cb => {
    if (!user.actions)
      return cb()

    async.map(user.actions, (r, cb) => {
      if (!r.agent)
        return cb()

      return cb(null, r.agent)

unread.js

GitHub: HomieOmie/nodebb-temp

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        (topicScores[index] < cutoff ||
        !!(userScores[index] && userScores[index] >= topicScores[index]));
    return { tid: tid, read: read, index: index };
});

return await async.map(result, async (data) => {
    if (data.read) {
        return true;
    }
    const hasUnblockedUnread = await doesTidHaveUnblockedUnreadPosts(data.tid, {

+ 7 other calls in file

topics.js

GitHub: HomieOmie/nodebb-temp

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    await topics.reply({ uid: topic.userId, content: 'topic 2 reply', tid: topic2Result.topicData.tid });
});

it('should get sorted topics in category', (done) => {
    const filters = ['', 'watched', 'unreplied', 'new'];
    async.map(filters, (filter, next) => {
        topics.getSortedTopics({
            cids: [category.cid],
            uid: topic.userId,
            start: 0,

+ 3 other calls in file

provider.js

GitHub: modeverv/musicdb_dev

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function loadBatch (targets, done) {
  if (!done) {
    return common.merge(targets.map(loadStoreSync));
  }

  async.map(targets, loadStore, function (err, objs) {
    return err ? done(err) : done(null, common.merge(objs));
  });
}

runtime.js

GitHub: mehdigoom/ValjangEngine-3.0.x-server

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async.detect = _createTester(async.eachOf, identity, _findGetResult);
async.detectSeries = _createTester(async.eachOfSeries, identity, _findGetResult);
async.detectLimit = _createTester(async.eachOfLimit, identity, _findGetResult);

async.sortBy = function (arr, iterator, callback) {
    async.map(arr, function (x, callback) {
        iterator(x, function (err, criteria) {
            if (err) {
                callback(err);
            }

+ 21 other calls in file

reflectAll.js

GitHub: mitchellporter/async.js-playground

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var async_functions = async.reflectAll([first, second, third, fourth]);
async.parallel(async_functions, (err, results) => {
    console.log(`Error: ${err}`);
    console.log(`Results length: ${results.length}`);

    async.map(results, (result, callback) => {
        if (result.error) console.log(`We can handle error logging here: ${result.error}`);
        callback();
    });
});

my_version.js

GitHub: Dalakoti07/web-dev

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    return chunkName;
}

chunkLength = getChunksLengthForWorker(i);

map(Array.from(getChunkArrayForWorker(i, chunkLength)), mapper, (error, results) => {
  if (error) {
    callback(error);
  } else {
    reduce(Object.entries(Object.assign({}, ...results)), reducer, callback);

+ 5 other calls in file

Live.js

GitHub: josebrwn/csgo-livegames

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const $ = cheerio.load(body);
const $live_matches = $('.live-match');
var results = [];

async.map($live_matches, ($m, next) => {
  // for each match in $live_matches, load it to $m
  const $ = cheerio.load($m);
  const _a = $('a.a-reset');
  _a.map((index, element) => {

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