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HTTP for JavaScript

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Mach is an HTTP server and client library that runs in both node.js and the browser. It has the following goals:

  • Simplicity: straightforward mapping of HTTP requests to JavaScript function calls
  • Asynchronous: responses can be deferred using Promises/A+ promises
  • Streaming: request and response bodies can be streamed
  • Composability: middleware composes easily using promises
  • Robustness: promises propagate errors up the call stack, simplifying error handling


Writing a "Hello world" HTTP server in Mach is simple.

var mach = require('mach');
mach.serve(function (conn) {
  return "Hello world!";

All mach applications receive a single argument: a Connection object. This object contains information about both the request and the response, as well as metadata including the method used in the request, the location of the request, the status of the response, and some helper methods.

Applications can send responses asynchronously using JavaScript promises. Simply return a promise from your app that resolves when the response is ready.

var app = mach.stack();
app.get('/users/:id', function (conn) {
  var id =;
  return getUser(id).then(function (user) {
    conn.json(200, user);

The call to app.use above illustrates how middleware is used to compose applications. Mach ships with the following middleware:

Please check out the source of a middleware file for detailed documentation on how to use it.


Writing an HTTP client is similarly straightforward.

var mach = require('mach');
mach.get('').then(function (conn) {
  console.log(conn.status, conn.response.headers, conn.responseText);

By default client responses are buffered and stored in the responseText connection variable for convenience. However, if you'd like to access the raw stream of binary data in the response, you can use the binary flag.

var fs = require('fs');
  url: '',
  binary: true
}).then(function (conn) {
  conn.responseText; // undefined 


Because all Mach applications share the same signature, it's easy to combine them in interesting ways. Mach's HTTP proxy implementation illustrates this beautifully: a proxy is simply an application that forwards the request somewhere else.

var proxyApp = mach.createProxy('');
// In a server environment we can use the mach.proxy middleware 
// to proxy all requests to the proxy's location. 
app.use(mach.proxy, proxyApp);
// In a client application we can call the proxy directly to 
// send a request to the proxy's location., {
  params: {
    username: 'mjackson'


Using npm:

$ npm install mach

Or, include lib/umd/mach.min.js in a <script> tag:

<script src="mach.min.js"></script>


Please file issues on the issue tracker on GitHub.


To run the tests in node:

$ npm install
$ npm test

The Redis session store tests rely on Redis to run successfully. By default they are skipped, but if you want to run them fire up a Redis server on the default host and port and set the $WITH_REDIS environment variable.

$ WITH_REDIS=1 npm test

To run the tests in Chrome:

$ npm install
$ npm run test-browser