Express connect middleware to provide easy frontend caching for Node.js

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README.md

Cachify

connect-cachify makes having proper browser cache and HTTP caching behavior for assets easier.

It is a set of middleware and view helper functions for the Node.js express framework.

This does not provide in-memory caching, middleware caching, or many other types of caching. Cachify is focused on reducing the number of HTTP requests to your web nodes.

Installation

npm install connect-cachify

How to Use

Instructions below are for Express 2, but Express 3 is also supported.

var app,
    express = require('express'),
    cachify = require('connect-cachify'),

app = express.createServer();

Middleware

var assets = {
    "/js/main.min.js": [
      '/js/lib/jquery.js',
      '/js/magick.js',
      '/js/laughter.js'
    ],
    "/css/home.min.css": [
      '/css/reset.css',
      '/css/home.css'
    ],
    "/css/dashboard.min.css": [
      '/css/reset.css',
      '/css/common.css',
      '/css/dashboard.css'
    ]
};

var url_to_paths = {
  '/js/jquery.js': '/home/development/jquery/jquery.js',
  '/css/reset.css': '/home/development/css-reset/reset.css'
};

app.use(cachify.setup(assets, {
  root: __dirname,
  url_to_paths: url_to_paths,
  production: your_config['use_minified_assets']
}));

setup takes two parameters: assets and options. Assets is an associative array where the keys are your production urls, and the value is a list of development urls that produce the same asset.

We'll discussion options in a section below.

Cachify middleware is now enabled. Let's look at this after hooking up the view helpers.

Note: You must put cachify.setup before static or other connect middleware which works with these same requests.

In an EJS template

...
<head>
  <title>Dashboard: Hamsters of North America</title>
  <%- cachify_css('/css/dashboard.min.css') %>
</head>
<body>
...
  <%- cachify_js('/js/main.min.js') %>
</body>
...

In a Jade template

...
title= Dashboard: Hamsters of North America
meta(charset='utf-8')
| !{cachify_css('/css/dashboard.min.css')}
...
body
...
  | !{cachify_js('/js/main.min.js')}
  block scripts

In production mode, a call to cachify_js will produce a single script tag like:

<script src="/js/fa6d51a13a245a90aeb48eeca0e52396/main.min.js"></script>

When production was set to false, cachify_js will produce:

<script src="/js/lib/jquery.js"></script>
<script src="/js/magick.js"></script>
<script src="/js/laughter.js"></script>

The middleware makes caching transparent. A request for /fa6d51a13a245a90aeb48eeca0e52396/js/main.min.js will have the req.url rewritten to /js/main.min.js, so that other middleware will work properly.

The middleware sets the cache expiration headers to the Mayan Apocalypse, and does it's best to ensure browsers won't request that version of /js/main.min.js again.

A goal is for this module to work well with other connect compilers, such as LESS or connect-assets.

Options

The following are optional config for cachify.setup

root - Path where static assets are stored on disk. Same value as you'd pass to the static middleware.
url_to_paths - an associative array of URLs to absolute filename paths. Useful to specify paths to files that are not in the root directory.
production - Boolean indicating if your in development or production mode. Effects how links for js and css files are generated.
debug - Boolean indicating we should always re-write urls with a hash.

For full details, see the API documentation.

Magick

So how does cachify work?

When you cachify a url, it adds an MD5 hash of the file's contents into the URL it generates:

http://example.com/cbcb1e865e61c08a68a4e0bfa293e806/stylo.css

Incoming requests are checked for this MD5 hash. If present and if we' know about the resource (either via options or the file exists on disk), then the request path is rewritten back to /stylo.css, so that another route can process the request.

These requests are served up with expires headers that are very long lived, so a user's browser will only request them once.

Cachify doesn't attempt to find an older version of your resource, if the MD5 has was for an older file.

Status

This module is brand spanking new. Please file issues with ideas, bugs, etc.

It was created as part of the BrowserID project.

Debugging

To debug cachify's hashed url behavior, pass in the following parameter in your options block:

setup({ debug: true, ...});

Now even in development mode, cache busting URLs will be generated, so you can troubleshoot any problems cachify magick is causing you.

Development

Patches are welcome! To run unit tests...

nodeunit test

Wordpress Cachify

Does this all sound like gobbledygook? Maybe you're looking for Wordpress cachify plugin instead of connect-cachify.