callbackify

v1.1.0
  • Types
  • ESM
  • CJS

backwards compatibilify your callback functions while migrating apis to promises

License
MIT
Deps
0
Install Size
-
Vulns
0
Published

Get started

$npm install callbackify
$pnpm add callbackify
$yarn add callbackify
$bun add callbackify
$deno add npm:callbackify
$vlt install callbackify

Readme

callbackify

backwards compatibilify your callback functions while migrating apis to promises

usage

var callbackify = require('callbackify')

var getUserById = callbackify(function (id) {
  // in this example, we're using [minq](https://npm.im/minq)
  return db.users.byId(id).first()
})

// later in your code, we can use a callback

getUserById(23, function (err, user) {
  if (err) { /* give up */ return }
  console.log('hello, ', user.name)
})

// but for newer code, we can consume it as a promise

getUserById(23).then(function (user) {
  console.log('hello, ', user.name)
}, function (err) {
  console.error(err)
})

callbackify will also preserve the this context of your functions:

getUserById.call({foo:true}, 12)
// the underlying promise-returning function is called with the supplied context argument

Normally, callbackify will only work with fixed-parameter-length functions, and will use the declared parameter length to determine if the extra callback argument is present. If you need to use callbackify with variadic functions, or functions that don't declare their full argument list, you can use:

// options argument is optional
var getUserById = callbackify.variadic(function (id, options) {
  if (options === undefined) { options = {} }
  if (options.select) {
    return db.users.byId(id).select(options.select).first()
  } else {
    return db.users.byId(id).first()
  }
})

// we can do either of these
getUserById(23, function (err, user) { })
getUserById(23, { select: [ 'name' ] }, function (err, user) {} )

Note that this will not work if the last argument your function can take is a function, as that last argument will always be detected as a callback function.

api

callbackify : (fn: (...args) => Promise ) => (...args, Callback) => Promise

Takes a Promise-returning function fn and returns a new function which can return a Promise or take a callback as the last parameter. If a callback is supplied, the function returns void. If no callback is supplied, the promise is returned.

installation

$ npm install callbackify

running the tests

From package root:

$ npm install
$ npm test

contributors

license

MIT. (c) MMXIII jden jason@denizac.org. See LICENSE.md

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Versions

1.1.0
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