Open Source JavaScript Browser Extensions and Plugins

Playwright is a Node.js library to automate Chromium, Firefox, and WebKit with a single API. Playwright is built to enable cross-browser web automation that is ever-green, capable, reliable and fast. Headless execution is supported for all browsers on all platforms. Playwright is built to automate the broad and growing set of web browser capabilities used by Single Page Apps and Progressive Web Apps. Scenarios that span multiple page, domains and iframes. Auto-wait for elements to be ready before executing actions (like click, fill). Intercept network activity for stubbing and mocking network requests. Emulate mobile devices, geolocation, permissions. Support for web components via shadow-piercing selectors. Native input events for mouse and keyboard. Upload and download files. The bridge between Node.js and the other languages is basically a Node.js runtime combined with Playwright which gets shipped for each of these languages (around 50MB).

SlimerJS is a scriptable browser. It allows you to manipulate a web page with an external Javascript script: opening a webpage, clicking on links, modifying the content... It is useful to do functional tests, page automation, network monitoring, screen capture etc. It is a tool like PhantomJs, except that it runs Gecko instead of Webkit, and it is headless when using Firefox 56+. It can be used with Firefox 59. Higher version of Firefox is not supported and probably will not be supported in the future, as the development is suspended for now. SlimerJS provides the same API of PhantomJS. The current version of SlimerJS is highly compatible with PhantomJS 2.1. See current release notes in docs/release-notes-*.rst, and read the compatibility table to know the implementation level. The main goal of SlimerJS is to allow to execute all scripts developed for PhantomJS. So you could use tools like CasperJS. In fact, CasperJs 1.1 and higher can be executed with SlimerJS!

It's a little different from other options because it doesn't use a headless browser to render content. This tradeoff allows Critters to be very fast and lightweight. It also means Critters inlines all CSS rules used by your document, rather than only those needed for above-the-fold content. Critters' design makes it a good fit when inlining critical CSS for prerendered/SSR'd Single Page Applications. It was developed to be an excellent compliment to the prerender-loader, combining to dramatically improve first paint time for most Single Page Applications. Import Critters into your Webpack configuration and add it to your list of plugins. That's it! Now when you run Webpack, the CSS used by your HTML will be inlined and the imports for your full CSS will be converted to load asynchronously. Create a Critters plugin instance with the given options.