Sign Up for Free

RunKit +

Try any Node.js package right in your browser

This is a playground to test code. It runs a full Node.js environment and already has all of npm’s 400,000 packages pre-installed, including thenify with all npm packages installed. Try it out:

var thenify = require("thenify")

This service is provided by RunKit and is not affiliated with npm, Inc or the package authors.

thenify v3.3.0

Promisify a callback-based function

thenify

NPM version Build status Test coverage Dependency Status License Downloads

Promisify a callback-based function using any-promise.

  • Preserves function names
  • Uses a native promise implementation if available and tries to fall back to a promise implementation such as bluebird
  • Converts multiple arguments from the callback into an Array, also support change the behavior by options.multiArgs
  • Resulting function never deoptimizes
  • Supports both callback and promise style

An added benefit is that thrown errors in that async function will be caught by the promise!

API

fn = thenify(fn, options)

Promisifies a function.

Options

options are optional.

  • options.withCallback - support both callback and promise style, default to false.

  • options.multiArgs - change the behavior when callback have multiple arguments. default to true.

    • true - converts multiple arguments to an array
    • false- always use the first argument
    • Array - converts multiple arguments to an object with keys provided in options.multiArgs
  • Turn async functions into promises

var thenify = require('thenify');

var somethingAsync = thenify(function somethingAsync(a, b, c, callback) {
  callback(null, a, b, c);
});
  • Backward compatible with callback
var thenify = require('thenify');

var somethingAsync = thenify(function somethingAsync(a, b, c, callback) {
  callback(null, a, b, c);
}, { withCallback: true });

// somethingAsync(a, b, c).then(onFulfilled).catch(onRejected);
// somethingAsync(a, b, c, function () {});

or use thenify.withCallback()

var thenify = require('thenify').withCallback;

var somethingAsync = thenify(function somethingAsync(a, b, c, callback) {
  callback(null, a, b, c);
});

// somethingAsync(a, b, c).then(onFulfilled).catch(onRejected);
// somethingAsync(a, b, c, function () {});
  • Always return the first argument in callback
var thenify = require('thenify');

var promise = thenify(function (callback) {
  callback(null, 1, 2, 3);
}, { multiArgs: false });

// promise().then(function onFulfilled(value) {
//   assert.equal(value, 1);
// });
  • Converts callback arguments to an object
var thenify = require('thenify');

var promise = thenify(function (callback) {
  callback(null, 1, 2, 3);
}, { multiArgs: [ 'one', 'tow', 'three' ] });

// promise().then(function onFulfilled(value) {
//   assert.deepEqual(value, {
//     one: 1,
//     tow: 2,
//     three: 3
//   });
// });

Metadata

RunKit is a free, in-browser JavaScript dev environment for prototyping Node.js code, with every npm package installed. Sign up to share your code.
Sign Up for Free