Installation

$ npm install accept-webp

Usage

var acceptWebp = require('accept-webp');
var express = require('express'); 
var app = express();

var staticPath = __dirname + '/static';

app.use(acceptWebp(staticPath, ['jpg', 'jpeg', 'png']));
app.use(express.static(staticPath));

Warning: accept-webp should be used before any middleware that is serving files (e.g. express.static) so that they know to serve the webp format file.

Overview

This is a piece of middlewear that can be used with Express and Connect.

This middlewear first looks at the Accept header of the HTTP request, and searches for image/webp. If the search is successful, it checks the filesystem for a file of the same name but with the .webp extension (myImage.webp instead of myImage.jpg). If it exists, req.url is changed so that other middleware (e.g. express.static) will serve webp format.
req.originalUrl is unchanged (unlike the pre-forked version), so all future middlewear can rely on the integrity of the originalUrl property.

Also upon success, the Vary header is set to Accept so that caching proxies can distingiuish which content to load for the same requested url.

The first argument of accept-webp (required) is the path to your static assets on the filesystem. It should generally be the same path that you pass to express.static. The second argument (optional) is either a single file extension (string) or a list of file extensions (array) for accept-webp to act upon.
accept-webp will not touch requests for file formats that are not in this list. If this argument is omitted, it defaults to ['jpg', 'png', 'jpeg'].

Why the fork?

• I didn't like the idea of parsing the User Agent string to determine file format support.
• I wanted the ability to define which file formats are looked at, and which are ignored
• The original version didn't allow the module to be used on multiple apps/routers each with different static file paths in Express. In other words, it shared the same path argument across each instance of the middlewear.
• The old version overwrote the Vary HTTP header, this one appends to it, so it's now more compatible with other modules such as (compression)[https://github.com/expressjs/compression].

License

The MIT License (MIT)

Copyright (c) 2014 Semenistyi Mykyta [email protected]
Copyright (c) 2015 Joshua Wise [email protected]

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.