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    map-each
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    1.0.0 • Public • Published

    map-each

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    map-each is a very small, flexible, parallel async mapping helper that has first-class support for Iterators (unlike other libraries, which mostly break with iterators) and concurrency. It also has complete TypeScript header files for comfortable integration.

    npm i map-each --save

    It is similar to async-iterate, now-and-later, async-parallel, ... and many other.

    const { mapEach } = require('map-each')
     
    mapEach(
      ['a', 'b', 'c']
      function (input, callback) {
        callback()
      },
      function (err) {
        // Done once all functions are done
      }
    )

    There are several things that make this different:

    • It returns an Iterable object instead of an Array.
    • It supports Promises in case you prefer to use async/await with your API's
    • It supports concurrency limits to limit the amount of commands executed at the same time.

    Iterable results

    Like in other libraries you can get the result, but unlike other libraries, its not an Array, so you need to apply an Array.from to it.

    mapEach([
      ['a', 'b']
      function (item, callback) {
        callback(null, 'name:' + item)
      },
    ], function (err, data) {
      Array.from(data) === ['name:a', 'name:b'] // the order is protected
    })

    Note: This is more of an internal detail, but if the passed-in function doesn't have a second parameter, the data will not be collected.

    mapEach([], function () {}, function () {
      console.log(arguments.length) // 1
    })
     
    mapEach([], function () {}, function (err, data) {
      console.log(arguments.length) // 2
    })

    Promise support

    If you don't pass in a callback handler at the end, it will automatically return a Promise.

    mapEach([/*...*/], function () {}).then(function () {
      // all done
    })

    Concurrency

    By passing a concurrency limit to the runner, it will limit the amount of parallel executions

    mapEach([/*...*/], function () {}, 1).then(function () {
      // now each operation is run in series.
    })
    mapEach([/*...*/], function () {}, 2).then(function () {
      // now two operations are run at the same time
    })

    License

    MIT

    Install

    npm i map-each

    DownloadsWeekly Downloads

    1

    Version

    1.0.0

    License

    MIT

    Unpacked Size

    15.6 kB

    Total Files

    11

    Last publish

    Collaborators

    • leichtgewicht