Run Async

Utility method to run a function either synchronously or asynchronously using a series of common patterns. This is useful for library author accepting sync or async functions as parameter. runAsync will always run them as an async method, and normalize the multiple signature.

Installation

 npm install --save run-async

Usage

Here's a simple example print the function results and three options a user can provide a function.

 var runAsync = require('run-async');

var printAfter = function (func) {
  var cb = function (err, returnValue) {
    console.log(returnValue);
  };
  runAsync(func, cb)(/* arguments for func */);
};

Using this.async

 printAfter(function () {
  var done = this.async();

  setTimeout(function () {
    done(null, 'done running with callback');
  }, 10);
});

Returning a promise

 printAfter(function () {
  return new Promise(function (resolve, reject) {
    resolve('done running with promises');
  });
});

Synchronous function

 printAfter(function () {
  return 'done running sync function';
});

Custom done factory

 var runAsync = require('run-async');

runAsync(function() {
  var callback = this.customAsync();
  callback(null, a + b);
}, 'customAsync')(1, 2)

Passing context to async method

 var runAsync = require('run-async');

runAsync(function() {
  assert(this.isBound);
  var callback = this.async();
  callback(null, a + b);
}).call({ isBound: true }, 1, 2)

runAsync.cb

runAsync.cb supports all the function types that runAsync does and additionally a traditional callback as the last argument signature:

 var runAsync = require('run-async');

// IMPORTANT: The wrapped function must have a fixed number of parameters.
runAsync.cb(function(a, b, cb) {
  cb(null, a + b);
}, function(err, result) {
  console.log(result)
})(1, 2)

If your version of node support Promises natively (node >= 0.12), runAsync will return a promise. Example: runAsync(func)(arg1, arg2).then(cb)

Licence

Copyright (c) 2014 Simon Boudrias (twitter: @vaxilart)
Licensed under the MIT license.