Dynamic Rendering with Rendertron

: Written by: J D; Category: News; Published: 31 January 2019; Hits: 287

Many frontend frameworks rely on JavaScript to show content. This can mean Google might take some time to index your content or update the indexed content.

A workaround we discussed at Google I/O this year is dynamic rendering. There are many ways to implement this. This blog post shows an example implementation of dynamic rendering using Rendertron, which is an open source solution based on headless Chromium.

Which sites should consider dynamic rendering?

Not all search engines or social media bots visiting your website can run JavaScript. Googlebot might take time to run your JavaScript and has some limitations, for example.

Dynamic rendering is useful for content that changes often and needs JavaScript to display.

Your site's user experience (especially the time to first meaningful paint) may benefit from considering hybrid rendering (for example, Angular Universal).

How does dynamic rendering work?

Dynamic rendering means switching between client-side rendered and pre-rendered content for specific user agents.

You will need a renderer to execute the JavaScript and produce static HTML. Rendertron is an open source project that uses headless Chromium to render. Single Page Apps often load data in the background or defer work to render their content. Rendertron has mechanisms to determine when a website has completed rendering. It waits until all network requests have finished and there is no outstanding work.

This post covers:

Take a look at a sample web app
Set up a small express.js server to serve the web app
Install and configure Rendertron as a middleware for dynamic rendering

The sample web app

The “kitten corner” web app uses JavaScript to load a variety of cat images from an API and displays them in a grid.

Cute cat images in a grid and

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