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 mz with all npm packages installed. Try it out:

var mz = require("mz")

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

mz v2.7.0

modernize node.js to current ECMAScript standards

MZ - Modernize node.js

NPM version Build status Test coverage Dependency Status License Downloads

Modernize node.js to current ECMAScript specifications! node.js will not update their API to ES6+ for a while. This library is a wrapper for various aspects of node.js' API.

Installation and Usage

Set mz as a dependency and install it.

npm i mz

Then prefix the relevant require()s with mz/:

var fs = require('mz/fs')

fs.exists(__filename).then(function (exists) {
  if (exists) // do something

With ES2017, this will allow you to use async functions cleanly with node's core API:

const fs = require('mz/fs')

async function doSomething () {
  if (await fs.exists(__filename)) // do something


Many node methods are converted into promises. Any properties that are deprecated or aren't asynchronous will simply be proxied. The modules wrapped are:

  • child_process
  • crypto
  • dns
  • fs (uses graceful-fs if available)
  • readline
  • zlib
var exec = require('mz/child_process').exec

exec('node --version').then(function (stdout) {

Promise Engine

mz uses any-promise.


Can I use this in production?

Yes, Node 4.x ships with stable promises support. For older engines, you should probably install your own promise implementation and register it with require('any-promise/register')('bluebird').

Will this make my app faster?

Nope, probably slower actually.

Can I add more features?

Sure. Open an issue.

Currently, the plans are to eventually support:

  • New APIs in node.js that are not available in older versions of node
  • ECMAScript7 Streams


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