Async Harmony

async-harmony is a module for managing asynchronous control flow using Generators

Status

As of 15 May 2014 this module is tested only in Firefox 29 running on Ubuntu

Harmony Syntax Features Used

Generators (yield), arrow functions, let, default function params, For..of loops

Take a look at the ECMAScript 6 compatibility table

Install

$ npm install async-harmony

You can also use this module as an amd module or a global object in the browser

Tests

Tests

Examples

Examples

Methods

series(jobs, done, kill=true)

Process a list of tasks sequentially

• jobs - [] or {} of jobs to execute
  • each job is function(args, done) where
  • args - contains the results from all previous jobs, and intermediate results passed between the jobs
  • done(err, result) - return error and result
• done(err, result) - callback to execute once all jobs are done
• kill - true or false - determines whether to stop the job queue on first error received or not

async.series({
  job1: (args, done) => {
    done(null, 'result1');
  },
  job2: (args, done) => {
    done(null, 'result2');
  }
}, (err, result) => {
  result == {job1:'result1', job2:'result2'}
});

examples

eachSeries (items, job, done, kill=true)

Process a list of items sequentially

• items - [] of items to process
• job - function(err, done) to execute for each item
  • done(err, result) - return error and result
• done(err, result) - callback to execute once all items are processed
• kill - true or false - determines whether to stop the job queue on first error received or not

async.eachSeries([0,1], (item, done) => {
  done(null, 'result'+item);
}, (err, result) => {
  result == ['result0', 'result1']
});

examples

each (items, job, done, kill=false)

Process a list of items in parallel

• items - [] of items to process
• job - function(err, done) to execute for each item
  • done(err, result) - return error and result
• done(err, result) - callback to execute once all items are processed
• kill - true or false - determines whether to stop the job queue on first error received or not

async.each([0,1], (item, done) => {
  done(null, 'result'+item);
}, (err, result) => {
  result == ['result0', 'result1']
});

examples

eachLimit (limit, items, job, done, kill=false)

Process a list of items in parallel, limiting the number of items to process simultaneously

• limit - number of items to process simultaneously
• items - [] of items to process
• job - function(err, done) to execute for each item
  • done(err, result) - return error and result
• done(err, result) - callback to execute once all items are processed
• kill - true or false - determines whether to stop the job queue on first error received or not

async.eachLimit(2, [0,1,2], (item, done) => {
  done(null, 'result'+item);
}, (err, result) => {
  result == ['result0', 'result1', 'result2']
});

examples

parallel (jobs, done, kill=false)

Process a list of tasks in parallel

• jobs - [] or {} of jobs to execute
  • each job is function(done) where
  • done(err, result) - return error and result
• done(err, result) - callback to execute once all jobs are done
• kill - true or false - determines whether to stop the job queue on first error received or not

async.parallel({
  job1: (done) => {
    done(null, 'result1');
  },
  job2: (done) => {
    done(null, 'result2');
  }
}, (err, result) => {
  result == {job1:'result1', job2:'result2'}
});

examples

parallelLimit (limit, jobs, done, kill=false)

Process a list of tasks in parallel, limiting the number of tasks to process simultaneously

• limit - number of jobs to process simultaneously
• jobs - [] or {} of jobs to execute
  • each job is function(done) where
  • done(err, result) - return error and result
• done(err, result) - callback to execute once all jobs are done
• kill - true or false - determines whether to stop the job queue on first error received or not

async.parallelLimit(2, {
  job1: (done) => {
    done(null, 'result1');
  },
  job2: (done) => {
    done(null, 'result2');
  },
  job3: (done) => {
    done(null, 'result3');
  }
}, (err, result) => {
  result == {job1:'result1', job2:'result2', job2:'result3'}
});

examples

forever (job, done)

Execute a task indefinitely (or until an error occur)

• job - task to execute
  • job is function(done) where
  • done(err) - return error
• done(err) - callback to execute if an error occur

var b = false;
async.forever((done) => {
  setTimeout(() => {
    b = !b;
    console.log(b ? 'tik' : 'tak');
    done();
  }, 1000);
}, (err) => {
  if (err) console.log('Clock stopped!');
});

examples

until (test, job, done)

Execute a task until test condition becomes true

• test - test to execute for each iteration
• job - task to execute
  • job is function(done) where
  • done(err) - return error
• done(err) - callback to execute when the test condition is met or if an error occur

var count = 0;
async.until(
  () => (count == 5),
  (done) => {
    setTimeout(() => {
      console.log(++count, 'seconds passed!');
      done();
    }, 1000);
  },
  (err) => {
    if (err) console.log('Counter broke!');
    else console.log('Done: 5 seconds passed!');
  }
);

examples

whilst (test, job, done)

Execute a task while test condition is true

• test - test to execute for each iteration
• job - task to execute
  • job is function(done) where
  • done(err) - return error
• done(err) - callback to execute when the test condition becomes false or if an error occur

var count = 0;
async.whilst(
  () => (count < 5),
  (done) => {
    setTimeout(() => {
      console.log(++count, 'seconds passed!');
      done();
    }, 1000);
  },
  (err) => {
    if (err) console.log('Counter broke!');
    else console.log('Done: 5 seconds passed!');
  }
);

examples

License

(The MIT License)

Copyright (c) 2014 simov <[email protected]>

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.