middleware

rendertron-middleware

An Express middleware for Rendertron.

Rendertron is a server which runs headless Chrome and renders web pages on the fly, which can be set up to serve pages to search engines, social networks and link rendering bots.

This middleware checks the User-Agent header of incoming requests, and if it matches one of a configurable set of bots, proxies that request through Rendertron.

Usage

$ npm install --save express rendertron-middleware

const express = require('express');
const rendertron = require('rendertron-middleware');

const app = express();

app.use(rendertron.makeMiddleware({
  proxyUrl: 'http://my-rendertron-instance/render',
}));

app.use(express.static('files'));
app.listen(8080);

Configuration

The makeMiddleware function takes a configuration object with the following properties:

Property	Default	Description
proxyUrl	Required	Base URL of your running Rendertron proxy service.
userAgentPattern	A set of known bots that benefit from pre-rendering. Full list.	RegExp for matching requests by User-Agent header.
excludeUrlPattern	A set of known static file extensions. Full list.	RegExp for excluding requests by the path component of the URL.
injectShadyDom	false	Force the web components polyfills to be loaded. Read more.
timeout	11000	Millisecond timeout for the proxy request to Rendertron. If exceeded, the standard response is served (i.e. next() is called). This is not the timeout for the Rendertron server itself. See also the Rendertron timeout.