Recent Articles

  • Implementing Private Fields for JavaScript

    When implementing a language feature for JavaScript, an implementer must make decisions about how the language in the specification maps to the implementation. Private fields is an example of where the specification language and implementation reality diverge, at least in SpiderMonkey– the JavaScript engine which powers Firefox. To understand more, I’ll explain what private fields are, a couple of models for thinking about them, and explain why our implementation diverges from the specification language.

  • Looking fine with Firefox 89

    Firefox 89 has smartened up and brings with it a slimmed-down, slightly more minimalist interface. Along with this new look, we get some great styling features including a force-colours feature for media queries and better control over how fonts are displayed. The long-awaited top-level await keyword for JavaScript modules is now enabled, as well as the PerformanceEventTiming interface, which is another addition to the performance suite of APIs: 89 really has been working out!

  • Improving Firefox stability on Linux

    Roughly a year ago at Mozilla we started an effort to improve Firefox stability on Linux. This effort quickly became an example of good synergies between FOSS projects.

  • Introducing Firefox’s new Site Isolation Security Architecture

    Like any web browser, Firefox loads code from untrusted and potentially hostile websites and runs it on your computer. To protect you against new types of attacks from malicious sites and to meet the security principles of Mozilla, we set out to redesign Firefox on desktop.

  • Pyodide Spin Out and 0.17 Release

    We are happy to announce that Pyodide has become an independent and community-driven project. We are also pleased to announce the 0.17 release for Pyodide with many new features and improvements. Pyodide consists of the CPython 3.8 interpreter compiled to WebAssembly which allows Python to run in the browser.

  • Never too late for Firefox 88

    April is upon us, and we have a most timely release for you — Firefox 88. In this release you will find a bunch of nice CSS additions including :user-valid and :user-invalid support and image-set() support, support for regular expression match indices, removal of FTP protocol support for enhanced security, and more! This blog post […]

  • QUIC and HTTP/3 Support now in Firefox Nightly and Beta

    Support for QUIC and HTTP/3 is now enabled by default in Firefox Nightly and Firefox Beta and we are planning to start a rollout on the release in Firefox Stable Release 88. HTTP/3 will be available by default by the end of May.

  • Eliminating Data Races in Firefox – A Technical Report

    We successfully deployed ThreadSanitizer in the Firefox project to eliminate data races in our remaining C/C++ components. In the process, we found several impactful bugs and can safely say that data races are often underestimated in terms of their impact on program correctness. We recommend that all multithreaded C/C++ projects adopt the ThreadSanitizer tool to enhance code quality.

  • A web testing deep dive: The MDN web testing report

    For the last couple of years, we've run the MDN Web Developer Needs Assessment (DNA) Report, which aims to highlight the key issues faced by developers building web sites and applications. This has proved to be an invaluable source of data for browser vendors and other organizations to prioritize improvements to the web platform. This year we did a deep dive into web testing, and we are delighted to be able to announce the publication of this follow-on work, available at our insights.developer.mozilla.org site along with our other Web DNA publications.

  • MDN localization in March — Tier 1 locales unfrozen, and future plans

    Since we last talked about MDN localization, a lot of progress has been made. In this post we'll talk you through the unfreezing of Tier 1 locales, and the next steps in our plans to stop displaying non-active and unmaintained locales.

  • In March, we see Firefox 87

    Nearing the end of March now, and we have a new version of Firefox ready to deliver some interesting new features to your door. This month, we've got some rather nice DevTools additions in the form of prefers-color-scheme media query emulation and toggling :target pseudo-classes, some very useful additions to editable DOM elements: the beforeinput event and getTargetRanges() method, and some nice security, privacy, and macOS screenreader support updates.

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