exstatic

Express middleware to help with the bundling, minifying, obfuscating and versioning of static assets for delivery over a CDN.

npm install exstatic
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exstatic

Connect/Express-style middleware to help with the bundling, minifying, obfuscating and versioning of static assets for delivery over a CDN.

Installation

$ npm install exstatic

Quick Start

var
express = require('express'),
exstatic = require('exstatic'),
staticAssets = exstatic(),
app = express();

staticAssets.createAssetsFromDirectory(
    '/static/:version/:dirname/:basename.:cacheId:extname',
    __dirname + '/public'
    );

app.use(staticAssets.middleware);

app.listen(80);

A directory structure like this:

app
 +- public
 |   +- css
 |   |   +- style.css
 |   +- js
 |       +- jquery.js
 |       +- app.js
 +- app.js

will generate asset URLs similar to the following:

GET /static/1359528874/css/style.d9b28cb1.css
GET /static/1359528874/js/jquery.83f534af.js
GET /static/1359528874/js/app.057d0df0.js

Usage

Startup options

exstatic can be started with some options to help structure generated URLs.

  • host: The host to prefix any generated URLs with.
  • cachePath: The path to store rendered file output.
  • version: A version string that may be used in the generated URLs.
  • noCleanup: Don't delete the files stored in the cache path when the application exits.
  • typeSearchPath: A string or an array of strings of paths that should be searched to find asset type libraries.
var exstatic = require('exstatic')
    staticAssets = exstatic({
                        host: 'http://example.com',
                        cachePath: __dirname + '/static_cache',
                        version: 'v1'
                    });

Specifying Assets

createAssetsFromDirectory(pattern, directory)

Creates versioned asset URLs from the contents of one or more directories.

Arguments

  • pattern: A pattern string to build the asset URLs. Variables in the pattern are preceded by a colon, just like path parameters in Express routing. The available variables are:

    • :path: The path of the asset relative to the directory argument from which is was found, stripped of all preceding ../, if any.
    • :dirname: The directory component of :path.
    • :basename: The filename component of :path, without the extension.
    • :extname: The file extension component of :path.
    • :version: The version string specified in the startup options (defaults to a unix timestamp of when exstatic is required).
    • :cacheId: A truncated MD5 hash of the file contents.
  • directory: A string or array of strings of directories of files to be served.

Example

staticAssets.createAssetsFromDirectory(
    '/static/:version/:dirname/:cacheId/:basename:extname',
    [
        './public/foo',
        './public/bar'
    ]
);

createAsset(type, settings)

Creates a single asset to be served with the specified settings.

Arguments

  • type: The preprocessing/compression strategy to use on this collection of files.
  • settings: An object containing the following parameters:

    • id (required): A string identifier for this asset.
    • pattern (required): A pattern string to build the asset URL. Variables in the pattern are preceded by a colon, just like path parameters in Express routing. Exstatic exposes the following variables:

      • :version: The version string specified in the startup options (defaults to a unix timestamp of when exstatic is required).
      • :cacheId: A truncated MD5 hash of the file contents.
    • files (required): An array of strings of file paths to be processed and/or compressed per the type argument, and be concatenated into a single file.

    Note: Some asset types may define additional settings.

Example

staticAssets.createAsset(
    'javascript',
    {
        id: 'js/lib.js',
        pattern: '/static/:version/js/:cacheId/lib.js',
        files: [
            './public/lib/js/underscore.js',
            './public/lib/js/jquery.js',
            './public/lib/js/jquery.form2json.js',
            './public/lib/js/jquery.locus.js',
            './public/lib/js/backbone.js'
        ]
    }
);

middleware

In order to start serving the defined assets and reference their generated URLs from your templates, the exstatic middleware method must be used by your Express application:

var
express = require('express'),
exstatic = require('exstatic')
staticAssets = exstatic(),
app = express();

// assets get defined here
// express configuration gets started here

app.use(staticAssets.middleware);

app.listen(80);

Referencing the assets from templates

N.B.: Currently, exstatic only provides a means for referencing assets for Mustache-style languages like Hogan.js and handlebars.js. (I'll gladly accept patches to extend support!)

To render the CDN-friendly asset URL from the asset defined in the above createAsset example, just use the {{#staticAssets}} lambda:

<!DOCTYPE html>
<html>
    <head>
        <title>exstatic!</title>

        <script type="text/javascript" src="{{#staticAssets}}js/lib.js{{/staticAssets}}></script>
    </head>
    <body>
    </body>
</html>

Assets

Assets are the fundamental building block of exstatic. They are the definitions of static content your application will serve, with the help of exstatic's middleware.

Asset Types

When creating assets using createAsset, a type must be specified as the first argument. The following types are currently available:

Built-in

  • javascript: The javascript type uses UglifyJS to obfuscate and compress the supplied files before concatenating them into a single asset.
  • stylus: The stylus type uses Stylus to generate CSS from -- what else -- stylus files before compressing and concatenating them into a single asset.
  • png: The png type can only handle a single PNG image in it's files array. It will run optipng using node-optipng on the file and serve the compressed version.

Additional Types

Additional types can be created simply by inheriting the Asset object defined in lib/Asset.js. The built-in types (in lib/assets/) can help in getting started.

To use your own types, make sure the folder they're kept in is included in the typeSearchPath setting initially passed to exstatic.

Asset Variations

An individual asset may have multiple variations. Asset variations are distinguished by the values used for variables in the Asset's pattern, which defines a unique URL for the variation. Exstatic defines and assigns values for some pattern variables by default, namely, version and cacheId. Additional pattern variables can be defined by a colon prefixed identifier in the Asset's pattern string (e.g., :myvariable), which can then be used to create additional variations of an Asset with the help of event handlers.

When an Asset's pattern is matched for an incoming request, but no matching variation exists to create a response, a new Asset variation is created. The new variation then enters the render pipeline to build a response. The render pipeline is a procedure generally represented by the following steps:

  1. The new Asset variation is initialized.
  2. Each of the component files of the Asset variation are processed as defined by the Asset type.
  3. Once all the files have been processed, the variation is cached and sent as a response.

Events

During the render process, the Asset variation maintains a cache of processed output of each file. Events are the means to modify the Asset variation and the output at various points of the render pipeline.

An Asset may emit the following events when building a new variation:

  • variantInit: emitted when a URL has no existing matching variations, and a new variation is initialized to build a response.
  • variantPreRender: emitted just before the process of rendering the Asset variation begins.
  • variantPreRenderFile: emitted before the process of rendering an individual file comprising the asset.
  • variantRenderFile: emitted after prerendering and just before rendering an individual file comprising the asset.
  • variantPostRenderFIle: emitted when rendering an individual file comprising the asset is complete.
  • variantPostRender: emitted when all files comprising the asset have completed rendering.
Handlers for variantInit, variantPreRender, and variantPostRender

Arguments

  • variant: a reference to the Asset variation.
  • callback: a function that when called, signals the render pipeline to resume processing the Asset variation. An error may be raised by passing an expression that evaluates to true as the first argument.
Handlers for variantPreRenderFile, variantRenderFile, and
  *variantPostRenderFile*

Arguments

  • variant: a reference to the Asset variation.
  • file: a string of the path of the file currently being processed. This can be used to get/set the current state of the output of the file using the following methods of the Asset variation:

    • getRenderCache(file): retrieve the current state of the output for the given file.
    • setRenderCache(file, contents): set the current state of the output for the given file.
  • callback: a function that when called, signals the render pipeline to resume processing the Asset variation. An error may be raised by passing an expression that evaluates to true as the first argument.

Examples

Examples are available with the git repository. Each requires Express v3.x, and should be run from within it's own directory.

Assuming express is installed and accessible from where git clone is run:

$ git clone git@github.com:2sidedfigure/exstatic.git
$ cd exstatic/examples/js
$ node index.js

Author

± ryan (ryan@2-si.de). Development was and continues to be sponsored by YellowBot.

License

Copyright (c) 2013 Ryan Ettipio

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE SOFTWARE.

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