always-callback

Create callback api for given sync function. Guarantee that given function (sync or async, no matter) will always have callback api and will handle errors correctly.

Install

npm i always-callback --save
npm test

Usage

For more use-cases see the tests

• <fn> {Function} function to transform
• return {Function} async function that must have callback

It is useful for control-flow and hybrid APIs

Example

var fs = require('fs')
var alwaysCallback = require('always-callback')
 
// if sync function given, transform it to async
var parse = alwaysCallback(JSON.parse)
var stringify = alwaysCallback(JSON.stringify)
var readFile = alwaysCallback(fs.readFileSync)
 
// if asynchronous function given, it remains async
var statFile = alwaysCallback(fs.stat)
 
parse('{"foo":"bar"}', function (err, res) {
  console.log(err) //=> null
  console.log(res) //=> { foo: 'bar' }
})
 
stringify({foo: 'bar', baz: 'qux'}, null, 2, function (err, res) {
  //=> it would prettify and stringify json
  console.log(err) //=> null
  console.log(res)
  //=> {
  //   "foo": "bar",
  //   "baz": "qux"
  // }
})
 
readFile('./package.json', 'utf8', function (err, res) {
  console.log(err) //=> null
  console.log(res) //=> { name: 'always-callback', ... }
})
 
statFile('./package.json', function (err, res) {
  console.log(err) //=> null
  console.log(res) //=> { dev: 64770, mode: 33204, ... }
})

Related

• make-callback: Make synchronous function to support callback api
• handle-callback: Initial step for creating hybrid APIs, used by hybridify. Handle callback in promise - give promise and callback return promise.
• handle-arguments: Handles given Arguments object - return separatly last argument (commonly callback) and other arguments as Array. Useful in node-style callback flow.
• manage-arguments: Prevents arguments leakage - managing arguments. From Optimization killers by Petka Antonov.
• is-async-function: Check that given function is async (callback) function or not. Trying to guess that based on check if callback or cb exists in function arguments.
• is-sync-function: Opposite of is-async-function. Check that given function is synchronous.
• is-empty-function: Checks the given function (or fn.toString()) is with empty body - dont have body.

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.

Charlike Make Reagent