kevbook.flow

flow

Simple & basic flow control with no dependencies. Its simple, fast. No BS. Its an extension of fastsync https://github.com/joekarl/fastsync.

Use it in browsify, webpack, node.js/io.js

Covers 4 basic use cases:

• parallel - Run functions in parallel and callback when finished
• series - Run functions in series and callback when finished
• waterfall - Run functions in series while passing results of one function to the next
• asyncMap - Convenience method for mapping an array using asynchronous functions, analogous to an async version of Array.forEach with all tasks kicked off in parallel
• seriesMap - Convenience method for mapping an array using asynchronous functions, analogous to an async version of Array.forEach with all tasks kicked off in series

Note about function resolution

All functions are resolved immediately, to delay/overhead of next tick of the event loop. If you need to evaluate on next tick, use either setImmediate or process.nextTick. Add a wrapper, probably on your functions.

Usage

$ npm install kevbook.flow --save
var flow = require('kevbook.flow');

Examples

parallel

flow.parallel([
  function one(cb) {
    setTimeout(function(){
        cb(null, 1);
    }, 100);
  },
  function two(cb) {
    setTimeout(function(){
        cb(null, 2);
    }, 100);
  },
  function three(cb) {
    setTimeout(function(){
        cb(null, 3);
    }, 100);
  },
  function four(cb) {
    setTimeout(function(){
        cb(null, 4);
    }, 100);
  }
], function(err, results){
  //100ms later
  console.log(results); //[1, 2, 3, 4]
});

series

flow.series([
  function one(cb) {
    setTimeout(function(){
        cb(null, 1);
    }, 100);
  },
  function two(cb) {
    setTimeout(function(){
        cb(null, 2);
    }, 100);
  },
  function three(cb) {
    setTimeout(function(){
        cb(null, 3);
    }, 100);
  },
  function four(cb) {
    setTimeout(function(){
        cb(null, 4);
    }, 100);
  }
], function(err, results){
  //400ms later
  console.log(results); //[1, 2, 3, 4]
});

waterfall

flow.waterfall([
  function(cb) {
    cb(null, 8);
  },
  function split(v, cb) {
    //v = 8
    cb(null, v / 2, v / 2);
  },
  function square(v1, v2, cb) {
    //v1 = 4, v2 = 4
    cb(null, v1 * v2);
  },
  function minus1(v, cb) {
    //v = 16
    cb(null, v - 1);
  }
], function(err, result){
  console.log(result); //15
});

parallelMap

Note Results can be processed in any order but will be returned in the order submitted

flow.parallelMap([1,2,3], function mult5(v, cb){
  setTimeout(function(){
    cb(null, v * 5);
  }, 100);
}, function(err, mappedArray){
  console.log(mappedArray); //[5,10,15]
});

seriesMap

flow.seriesMap([1,2,3], function mult5(v, cb){
    setTimeout(function(){
        cb(null, v * 5);
    }, 100);
}, function(err, mappedArray){
    console.log(mappedArray); //[5,10,15]
});