Skip to main content Documenting CSS , HTML , and JavaScript , since 2005. Featured articles Blog Celebrating 20 years of MDN MDN turns 20! Let's look at how we started, how MDN became the most trusted resource for web developers, the impact it's had on the open web, and yes, there's cake, too. Celebrating 20 years of MDN MDN turns 20! Let's look at how we started, how MDN became the most trusted resource for web developers, the impact it's had on the open web, and yes, there's cake, too. Web APIs Navigation API The Navigation API provides the ability to initiate, intercept, and manage browser navigation actions. It can also examine an application's history entries. This is a successor to previous web platform features such as the History API and window.location, which solves their shortcomings and is specifically aimed at the needs of single-page applications (SPAs). The Navigation API provides the ability to initiate, intercept, and manage browser navigation actions. It can also examine an application's history entries. This is a successor to previous web platform features such as the History API and window.location, which solves their shortcomings and is specifically aimed at the needs of single-page applications (SPAs). Web APIs Trusted Types API The Trusted Types API gives web developers a way to ensure that input has been passed through a user-specified transformation function before being passed to an API that might execute that input. This can help to protect against client-side cross-site scripting (XSS) attacks. Most commonly the transformation function sanitizes the input. Trusted Types API The Trusted Types API gives web developers a way to ensure that input has been passed through a user-specified transformation function before being passed to an API that might execute that input. This can help to protect against client-side cross-site scripting (XSS) attacks. Most commonly the transformation function sanitizes the input. CSS Using CSS anchor positioning The CSS anchor positioning module defines features that allow you to tether elements together. Elements can be defined as anchor elements and anchor-positioned elements. Anchor-positioned elements can be bound to anchor elements. The anchor-positioned elements can then have their size and position set relative to the size and location of the anchor elements to which they are bound. Using CSS anchor positioning The CSS anchor positioning module defines features that allow you to tether elements together. Elements can be defined as anchor elements and anchor-positioned elements. Anchor-positioned elements can be bound to anchor elements. The anchor-positioned elements can then have their size and position set relative to the size and location of the anchor elements to which they are bound. developer.mozilla.org Introducing the MDN MCP server 3 months ago MDN's MCP server brings MDN's documentation and browser compatibility data directly into your editor or IDE, giving your LLM or coding agent access to accurate, up-to-date web platform information. Introducing the MDN MCP server MDN's MCP server brings MDN's documentation and browser compatibility data directly into your editor or IDE, giving your LLM or coding agent access to accurate, up-to-date web platform information. developer.mozilla.org Under the hood of MDN's new frontend 5 months ago You may have spotted that MDN has a new frontend. There's plenty happening under the surface, so let's unpack the technologies we chose, the architectural decisions we made, and why we did a rebuild at all.

Under the hood of MDN's new frontend You may have spotted that MDN has a new frontend. There's plenty happening under the surface, so let's unpack the technologies we chose, the architectural decisions we made, and why we did a rebuild at all. developer.mozilla.org Image formats: Codecs and compression tools 10 months ago Image compression involves countless trade-offs between quality, size, and speed. In this final part of the series, we experiment with codecs, metrics, and tools to find practical ways to balance efficiency and visual fidelity. Image formats: Codecs and compression tools Image compression involves countless trade-offs between quality, size, and speed. In this final part of the series, we experiment with codecs, metrics, and tools to find practical ways to balance efficiency and visual fidelity. developer.mozilla.org A beginner-friendly guide to view transitions in CSS 11 months ago Learn how to bring smooth, animated navigation to multi-page apps with view transitions. With just one line of CSS, you can enable seamless transitions between pages. A beginner-friendly guide to view transitions in CSS Learn how to bring smooth, animated navigation to multi-page apps with view transitions. With just one line of CSS, you can enable seamless transitions between pages. Recent contributions mdn/translated-content 10 hours ago 2026/09/05 時点の英語版に基づき更新 mdn/translated-content 10 hours ago Sep 1, 2026の英語版に対応 mdn/translated-content 10 hours ago Sep 5, 2026の英語版に対応 mdn/content 6 hours ago Hyphenate leftover user-defined modifiers mdn/content 6 hours ago Hyphenate leftover user-provided modifiers mdn/content 6 hours ago Hyphenate leftover out-of-date modifier mdn/content 6 hours ago Use third-party rather than leftover 3rd party mdn/content 5 hours ago Fix undefined helpers in the MediaSession play/pause example, make it live sample Contributor Spotlight