What new web platform features arrived in Microsoft Edge for developers in September 2026?

Text ranges inside form inputs finally get an API

The OpaqueRange API gives developers live access to ranges of text within form inputs such as textarea and input elements. You can use these ranges for operations like getBoundingClientRect and getClientRects to position UI at specific places within form inputs. The API also works with the CSS Custom Highlight API making it possible to create personalized highlights within editable text regions. Microsoft published an intro video explainer and live demos for the feature. This matters.

Accessibility gaps in shadow DOM components receive a fix

A common pain point developers face when creating web components with Shadow DOM is making them accessible. The problem is known as cross-root ARIA. The referenceTarget property of a ShadowRoot object solves this. It can also be set via the shadowrootreferencetarget HTML attribute on elements. This makes it possible to forward ID reference attributes such as for or aria-labelledby to elements that are inside the shadow DOM of a component. For example you can link a label for element to the right input element even if that input is inside the shadow DOM of a web component. The blog post shows a checkbox example where the template uses shadowrootmode open and shadowrootreferencetarget real-checkbox.

Composite widgets with multiple actionable parts have been hard to make accessible to assistive technology users. The new HTML aria-actions attribute makes it possible to expose your widgets secondary actions to screen readers. A tab widget with a close button can expose that button using aria-actions close-tab on the button element with the close span carrying the matching id. The ARIA Authoring Practices Guide provides a tabs with action buttons example.

Media styling pseudo-classes and PWA window controls land

Media pseudo-classes allow you to style media elements such as video and audio based on their playback state. The new pseudo-classes are playing paused buffering muted and stalled. The window-drag CSS property provides a standardized way to make installed PWA windows draggable which helps when using the Window Controls Overlay API. Starting with Microsoft Edge 151 on Windows when you use the Window Controls Overlay API the PWA app title bar is now hidden by default giving you more control over the look and feel of your app.

JavaScript iterator methods and performance entries expand the toolkit

New JavaScript Iterator methods make it easier to work with iterators. Iterator.join returns a string that is the concatenation of all elements produced by the iterator. Iterator.zip and Iterator.zipKeyed create new iterators that aggregate elements from multiple iterable objects. These methods zip the input iterables together allowing simultaneous iteration over the input iterables. The soft-navigation and interaction-contentful-paint performance entries help you improve performance of modern single-page web apps by measuring soft navigations that update the page without triggering traditional page browser history changes. The alpha CSS function creates a new color by adjusting another color's transparency. textStream is now available on Response Request and Body objects making it more convenient to process text incrementally without manually decoding byte chunks. The camera and microphone HTML elements are browser-provided buttons that let users toggle camera or microphone streams and when needed connect the permission request directly to an explicit user action.

Features ready for testing include WebMCP and new debugging tools

WebMCP is a web API that helps you create efficient fast and trusted human-agent collaboration workflows for your site. Using WebMCP you can reuse your existing front-end code and expose it as structured tools which a browsing agent can then use to help users accomplish tasks on your site. The implementation of the WebMCP spec in Microsoft Edge is ready for testing. Microsoft created a few samples and a browser extension to run and debug your WebMCP tools on the webmcp-labs repo.

The JS Self-Profiling API measures your app's performance in production on real user devices but it only samples your page's JavaScript leaving unexplained gaps in a trace. Microsoft is adding sample markers to fill those gaps. Each sample can now carry a marker that identifies what the browser was doing at capture time such as styling layout painting or garbage collection. An unexplained gap shows up clearly as a run of layout markers so you can pinpoint the real cause of a slow trace. A feature explainer live demo and origin trial registration are available.

Starting with Edge 153 the Network tool in DevTools includes two new actions available on each request via the contextual menu. Resend resends a request such as XHR or Fetch. Edit and resend as fetch creates a Fetch API call but does not send it right away instead writing it to the input of the Console tool where you can modify the new request such as by changing request headers or parameters and then send it. These features are planned to replace the experimental Network Console tool.

Updated versions of the Web Install API and the install element are available for testing. Both navigator.install and the install element now take a direct link to the target manifest file of the app you are installing. You can install the current app with navigator.install or a cross-origin web app by passing a manifest URL. The install element works similarly with a manifest attribute. Demos resources and origin trial registration are available.

Ecosystem updates round out the announcement

The Interop 2027 call for proposals is open and closes soon. Microsoft Edge sponsors Open Web Docs for the seventh consecutive year. A native menu element is coming with the Open UI community working on it. Google has implemented the menubar element which you can test by enabling the Experimental Web Platform features flag on the about://flags page.