The Fox and the Bolt: Bringing WebContainers to Firefox

WebContainers, a technology developed by StackBlitz, has recently become compatible with Firefox, marking a significant milestone in enabling Node runtime to operate on this browser. This achievement involved overcoming numerous technical challenges, particularly around cross-origin isolation and adapting to Firefox’s distinct JavaScript engine. The project exposed several bugs in both Firefox and Node, demonstrating how complex tools like WebContainers can stress test browser engines. While some issues were resolved with polyfills, others highlighted limitations in existing standards and browser-specific behaviors, such as differences in message scheduling and error stack trace generation. The development process also revealed discrepancies in how different browsers implement certain features, emphasizing the need for standardized cross-browser testing tools, which remain inadequate in 2022. Despite these challenges, the project has enhanced the understanding of cross-browser compatibility and laid the groundwork for future initiatives, including potential support for mobile browsers.