prerenderspaplugin

prerender-spa-plugin is a Webpack plugin designed to prerender the HTML of routes in a single-page application at build time. Its primary purpose is to generate static HTML snapshots that can be served to search engines and users, providing better SEO and faster initial content for environments where JavaScript execution is limited or slow.

The plugin works by launching a lightweight server to serve the built assets and then using a headless browser to visit each configured route. For every route, it waits for the page to finish rendering, captures the resulting HTML, and writes it to the corresponding location in the output directory. This process results in static HTML files alongside the usual JavaScript bundles, allowing crawlers that do not execute JS to receive meaningful content.

Configuration typically centers on a few key options. staticDir points to the directory containing the built assets. routes is an array of URL paths to prerender, such as '/', '/about', and '/contact'. renderer selects the rendering engine, commonly a Puppeteer-based renderer, though older setups may use a PhantomJS-based option. Additional timing controls like renderAfterTime or renderAfterElementExists help determine when a page is considered ready. postProcessHtml and postProcess allow modification of the HTML after it is rendered. The plugin is usually instantiated in the webpack.config.js with new PrerenderSpaPlugin({ ...options... }).

Limitations include that prerendering captures a snapshot at build time and may not reflect subsequent data loaded asynchronously. It can increase build duration and requires compatibility between the plugin, Webpack version, and the chosen headless browser renderer. For dynamic content that changes after load, alternative approaches such as server-side rendering or static site generation may be more appropriate.