async-simple-iterator

Making simple iterator for async lib that adds beforeEach, afterEach, error hooks and support for settling. It also emits beforeEach, afterEach and error events.

Install

npm i async-simple-iterator --save

Usage

For more use-cases see the tests

var base = require('async-simple-iterator')
// or get constructor
var AsyncSimpleIterator = require('async-simple-iterator').AsyncSimpleIterator

API

AsyncSimpleIterator

Initialize AsyncSimpleIterator with options.

Params

• options {Object=}: Pass beforeEach, afterEach and error hooks or settle:true.

Example

var ctrl = require('async')
var AsyncSimpleIterator = require('async-simple-iterator').AsyncSimpleIterator
 
var fs = require('fs')
var base = new AsyncSimpleIterator({
  settle: true,
  beforeEach: function (val) {
    console.log('before each:', val)
  },
  error: function (err, res, val) {
    console.log('on error:', val)
  }
})
var iterator = base.wrapIterator(fs.stat, {
  afterEach: function (err, res, val) {
    console.log('after each:', val)
  }
})
 
ctrl.map([
  'path/to/existing/file.js',
  'filepath/not/exist',
  'path/to/file'
], iterator, function (err, results) {
  // => `err` will always be null, if `settle:true`
  // => `results` is now an array of stats for each file
})

.wrapIterator

Wraps iterator function which then can be passed to async lib. You can pass returned iterator function to every async method that you want.

Params

• iterator {Function}: Iterator to pass to async lib.
• options {Object=}: Pass beforeEach, afterEach and error hooks or settle option.
• returns {Function}: Wrapped iterator function which can be passed to every async method.

Events

• emits: beforeEach with signature val[, value], next
• emits: afterEach with signature err, res, val[, value], next
• emits: error with signature err, res, val[, value], next

Example

var ctrl = require('async')
var base = require('async-simple-iterator')
 
base
  .on('afterEach', function (err, res, value, key, next) {
    console.log('after each:', err, res, value, key)
  })
  .on('error', function (err, res, value, key, next) {
    console.log('on error:', err, res, value, key)
  })
 
var iterator = base.wrapIterator(function (value, key, next) {
  console.log('actual:', value, key)
 
  if (key === 'dev') {
     var err = new Error('err:' + key)
     err.value = value
     next(err)
     return
   }
   next(null, 123 + key + 456)
 
}, {
  settle: true,
  beforeEach: function (value, key, next) {
    console.log('before each:', value, key)
  }
})
 
ctrl.forEachOf({
  dev: './dev.json',
  test: './test.json',
  prod: './prod.json'
}, iterator, function done (err) {
  // if settle:false, `err`
  // if settle:true, `null`
  console.log('end:', err)
})

Related

• async: Higher-order functions and common patterns for asynchronous code | homepage
• async-base-iterator: Basic iterator for async library that handles async and synchronous… more | homepage
• async-control: Ultimate asynchronous control flow goodness with built-in hook system and… more | homepage
• relike: Simple promisify a callback-style function with sane defaults. Support promisify-ing… more | homepage

Contributing

Pull requests and stars are always welcome. For bugs and feature requests, please create an issue.
But before doing anything, please read the CONTRIBUTING.md guidelines.

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