Hoxy

Hoxy is an HTTP traffic-sniffing and manipulation tool for JavaScript programmers.

Full Documentation

http://greim.github.io/hoxy/

Example

var hoxy = require('hoxy');
var proxy = hoxy.createServer().listen(8080);
proxy.intercept({

  // intercept during the response phase
  phase: 'response',

  // only intercept html pages
  mimeType: 'text/html',

  // expose the response body as a cheerio object
  // (cheerio is a jQuery clone)
  as: '$'
}, function(req, resp) {

  resp.$('title').text('Unicorns!');
  // all page titles will now say "Unicorns!"
});

Version 3.0

Hoxy has released version 3.0. This release simplifies the API and better supports ES6. Notable changes:

A done callback is no longer passed as the third arg to interceptors. Interceptor arity is, accordingly, no longer a switch for async behavior. Rather, it solely depends on the return type of the interceptor (i.e. promises or iterators over promises).
The third argument to interceptors is now the cycle object, === to this. This was based on a suggestion from @nerdbeere, with a view toward supporting arrow functions, in which this is lexical.
The CLI has been completely removed from the project. The reasoning is that, by simplifying the project, I can more easily maintain it. If there's a need, it can be brought back as a separate npm module. Perhaps somebody else can take that on.
Undocumented hoxy.forever() function goes away.

Release notes:

3.3.1 Merged PR #109. Thanks @nerdbeere.
3.3.0 Ability to filter by status.
3.2.2 Merged PR #95. Thanks devjerry.
3.2.1 Fixed test failures regarding content-length and transfer-encoding headers.
3.2.0 Better error handling. Added query getter/setter to request.
3.1.3 Merged PR #62. Thanks jonsharratt.
3.1.2 Make Proxy#log() chainable.
3.1.1 Prevent EADDRNOTAVAIL on Windows when using certAuthority.
3.1.0 Filtering options now accept functions.
3.0.3 Fixed Cycle#serve() breakage on Windows.
3.0.2 Fix for a Windows EADDRNOTAVAIL error.
3.0.1 Fixed bug where as intercepts weren't catching async errors properly.
3.0.0 Simplify the API and better support ES6.
2.3.1 Back-ported 3.0.1 async as intercept fix.
2.3.0 Added getter and setter for proxy-level slow options.
2.2.6 Added eslint npm script. Thanks @nerdbeere.
2.2.5 Fixed a bug where .buffer was always undefined. Thanks @Timwi.
2.2.4 Added babel optional runtime transformer.
2.2.3 Fixed broken reference to lodash-node in CLI.
2.2.2 Updated hoxy version in CLI.
2.2.1 Fixed error in npmignore.
2.2.0 Added proxy-level throttling.
2.1.1 Ditched babel require hook and instead use compile/prepublish.
2.1.0 Ability to run reversy proxy as an HTTPS server. Thanks @snoj.
2.0.0 Direct HTTPS proxying and improved async support in interceptors. Thanks @snoj, @Phoenixmatrix, @sholladay and others for helping with the HTTPS stuff!
1.2.4 Improved cheerio markup serialization. Thanks Seth Holladay.
1.2.3 Test command now npm test instead of mocha. Proxy close() method now passes args through to server close. Thanks Seth Holladay.
1.2.2 Fixed errors and test failures occurring on io.js.
1.2.1 Make listen() accept same args as native server.listen() instead of just port. Thanks Seth Holladay.
1.2.0 Send content-length whenever reasonably possible. (minor version bump since minor alteration to existing behavior)
1.1.5 Default protocol to 'http:' if not found because I'm a genius.
1.1.4 Default protocol to 'http' if not found.
1.1.3 Don't munge content-length headers unless necessary.
1.1.2 Burned a version number because I suck at npm.
1.1.1 Added SSL support for requests (protocol: https).
1.1.0 Added CLI functionality to scaffold new proxy projects.
1.0.5 Fixed static conditional get fail, flexible contentType matching, ability to set fullUrl.
1.0.4 npm distribution no longer contains test directory.
1.0.3 Fixed issue #21 causing breakage on windows, due to use of unix domain sockets.
1.0.2 Added tee() method to requests and responses, and accompanying tests.
1.0.1 Fixed bug with URL pattern matching, added filtering tests.
1.0.0 Initial release of Hoxy 1.0 rewrite.

Regarding Development of this Tool

I began writing code for this in 2010 while I worked at Cisco—and later at various startups—to solve my own needs for advanced testing and debugging production websites. The most common—although by no means only—use case for me was swapping in my own JavaScript onto web pages, in order to do rapid debugging without actually pushing console.logs to a staging server or (god forbid!) production. I could just edit a file on my local disk and reload my browser.

This enabled me to act quickly when hard-to-debug production issues arose, which translated into a competitive advantage for both myself and my company. Over time, however, I've used it less frequently, for a few reasons:

Devtools. Built-in debuggers got wayyy more powerful. Starting in ~2014, major browsers shipped with source-map-enabled debuggers, which allow setting breakpoints and stepping through code in original, non-uglified, non-bundled form. That was key, and alleviated 80% of what I need Hoxy for.
HTTPS everywhere. HTTPS became widely used in production during this same period. Hoxy supports HTTPS proxying, but involves extra setup, which adds friction to an already high-friction tool. Seriously, Hoxy makes it easier, but MITM-hacking your own HTTP traffic isn't exactly the definition of ease and simplicity.
Evergreen browsers. Happily, the amount of time I spend on cross-browser differences has gone down as of mid 2018. Along those lines, a secondary use for Hoxy was injecting code into older, single-digit versions of IE, which had zero devtools capabilities. Nowadays I simply don't bother with those browsers.
Functional programming. React (which I started using in 2014) is an enabling technology for functional programming. FP in turn makes it easier to test, debug, and reason about a piece of code in isolation. This even further alleviates the need to use Hoxy to see how something behaves in prod, since I can just write unit tests, reason about the code in my head, etc.

All of that said, this is still a valuable tool in my toolbox, and I use it when the need arises. I'm not putting much time and attention into bug fixes and feature improvements these days, but PRs are always welcome!

greim / hoxy