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Microsoft Edge 151 web platform release notes (Jul. 2026)

The following are the new web platform features and updates in Microsoft Edge 151, which releases on Jul. 30, 2026.

To stay up-to-date and get the latest web platform features, download a preview channel of Microsoft Edge (Beta, Dev, or Canary); go to Become a Microsoft Edge Insider.

Detailed contents:

Microsoft Edge DevTools

See What's new in Microsoft Edge DevTools.

WebView2

See Release notes for the WebView2 SDK.

CSS features

The following new Cascading Style Sheets (CSS) features are included in Microsoft Edge.

CSS ruby-overhang property

The ruby-overhang CSS property sets whether ruby annotations may overlap adjacent text.

The property accepts the auto, spaces and none values, to control overhang of ruby annotation text.

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Changed the position-anchor initial value to normal

The initial value for the position-anchor CSS property is now normal. Previously, the initial value was none.

This aligns Microsoft Edge with other browsers and with the anchor positioning specification.

  • If position-area is set to none, normal behaves like none.
  • If position-area is not set to none, normal behaves like auto.

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CSS alpha() function

The CSS alpha() function creates a new color by applying a specified alpha value to an existing color.

For example, alpha(from red / 0.5) creates a semi-transparent red color with 50% opacity.

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animation-trigger actions no longer auto-rewind

The values play, play-forwards and play-backwards of the animation-trigger CSS property instruct the animation trigger to play the animation.

These values don't automatically rewind the animation anymore: when the animation has already run to completion and play, play-forwards or play-backwards is used, the animation will not restart.

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HTML features

The following new HTML features are included in Microsoft Edge.

<usermedia> element

The <usermedia> HTML element is a browser-provided button that, upon activation, toggles camera or microphone streams. If required, the button prompts the user to choose whether to grant the page access to the camera and microphone.

This browser-provided button enables a better user experience, because the permission prompt is directly linked to the user intent.

The <usermedia> element was previously available as an origin trial under the more generic <permission> element. Based on feedback from developers and other browser vendors, the <permission> element has been renamed to the specific <usermedia> element, to provide a more tailored and powerful developer experience.

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Reference target

The referenceTarget property of a ShadowRoot object forwards attributes such as for, aria-labelledby, popovertarget, and commandfor to elements inside a shadow DOM. You can use this to, for example, link a <label> to its <input>, even if the <input> is in the shadow DOM of a web component.

When a shadow host specifies an element in its shadow tree to act as its reference target, all ID references that point to the shadow host are forwarded to the reference target element instead.

A reference target can also be set in HTML, by using the shadowrootreferencetarget attribute, like in the following example:

<label for="my-checkbox">Checkbox value</label>
<custom-checkbox id="my-checkbox">
  <template shadowrootmode="open" shadowrootreferencetarget="real-checkbox">
    <input id="real-checkbox" type="checkbox">
  </template>
</custom-checkbox>

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aria-actions attribute

The aria-actions HTML attribute exposes secondary actions for composite interactive widgets.

For example, you can use the aria-actions attribute to expose the close button of a tab, which is a secondary action for the tab widget, as follows:

<div class="tab" aria-actions="close-tab">
  Tab title
  <button id="close-tab">Close</button>
</div>

Secondary actions placed within composite interactive widgets is a common UI pattern. The aria-actions attribute allows you to expose these secondary action buttons directly, to improve discoverability for assistive technology (AT) users.

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shadowrootslotassignment attribute for declarative shadow DOM

The shadowrootslotassignment attribute of the <template> element allows declarative shadow roots to use manual slot assignment.

Previously, manual slot assignment was only available via JavaScript, as follows:

attachShadow({slotAssignment: "manual"})

You can now declare manual slot assignment via HTML, as follows:

<template shadowrootslotassignment="manual">
</template>

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Web APIs

The following new Web API features are included in Microsoft Edge.

Device event permission request API

You can call DeviceMotionEvent.requestPermission() and DeviceOrientationEvent.requestPermission() to ask the browser for device motion and orientation data to be shared with the webpage.

These methods return a promise that resolves to either granted or denied, based on whether the user has allowed the user agent to share sensor data with the page.

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Duplicate successive navigations are ignored

When a navigation is already in progress, Microsoft Edge now ignores a new navigation request to the same URL as the previous navigation request.

Duplicate navigations in quick succession are often caused by an accidental double-click. Duplicate navigations can waste resources by canceling the ongoing navigation and starting a new navigation. This optimization improves performance and improves the user experience.

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Cross-origin redirect timing in the Navigation Timing API

The Timing-Allow-Origin header, when used in chains of cross-origin redirects, provides values for redirectCount, redirectStart and redirectEnd to the destination document, via the Navigation Timing API.

This lets you measure and optimize your cross-origin redirects.

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LanguageDetector support for Traditional and Simplified Chinese

The LanguageDetector API can now detect and differentiate text that's written in Traditional Chinese or Simplified Chinese.

The LanguageDetector API returns the language code zh-Hant for Traditional Chinese, and zh-Hans for Simplified Chinese. Previously, the LanguageDetector API returned zh for both Traditional Chinese and Simplified Chinese.

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soft-navigation and interaction-contentful-paint performance entries

The Performance API now includes two new PerformanceEntry types:

  • soft-navigation - Reports same-document history-state changes that are initiated by interactions.
  • interaction-contentful-paint - Reports new contentful paints within parts of the page that were modified by a user interaction. This helps you understand interaction loading latency.

Use these new entries to measure the performance of soft navigations. A soft navigation is a JavaScript-driven navigation in a Single Page App (SPA).

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Exposed the FontFaceSet interface globally

The FontFaceSet interface is now exposed globally.

Previously, the FontFaceSet interface was not exposed as a global property.

This change aligns Microsoft Edge with the CSS Font Loading spec, and with Safari and Firefox.

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Speculation rules: form_submission field

You can now set the "form_submission": true field on a prerender rule in the Speculation Rules API, to allow the prerender to be activated by a form submission navigation.

Previously, form submissions could never activate a prerendered page. Now, setting "form_submission": true tells the browser to prepare the prerender, so that when the user submits a form whose result URL matches the prerendered URL, the prerender activates immediately.

This is useful for search forms where the result URL can be predicted in advance. For example, to prerender the result of a search form that navigates to /search?q=foo, use the following speculation rules:

<script type="speculationrules">
{
  "prerender": [
    {
      "urls": ["/search?q=foo"],
      "form_submission": true
    }
  ]
}
</script>

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Wheel event indicates whether a momentum scroll

The WheelEvent interface now includes a momentum attribute, which indicates whether the event is part of a momentum scroll.

The momentum attribute is useful, for example, on a device that has a trackpad, where the user can perform a fling gesture to scroll content. Many devices continue to fire wheel events for a while after trackpad motion stops, to simulate scrolling inertia. The momentum attribute differentiates those simulated events from the events that are fired during the physical trackpad interaction.

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XML parsing in Rust for non-XSLT scenarios

Microsoft Edge now uses a Rust-based XML parser, in scenarios where XSLT processing isn't required.

The Rust XML parser improves security by eliminating memory-corruption bugs in XML parsing. This applies to:

  • The DOMParser Web API.
  • The responseXML property on an XMLHttpRequest (XHR) object.
  • SVG documents.

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textStream() method for Response, Request, and Body

The Request, Response, and Blob interfaces now include a textStream() method.

The textStream() method provides a direct way to read text from a byte stream, without requiring first piping the stream through a TextDecoderStream().

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Origin trials

The following are origin trials for new experimental APIs that are available in Microsoft Edge.

Origin trials let you try experimental APIs on your own live website for a limited time. To learn more about origin trials, see Use origin trials in Microsoft Edge.

For the full list of available origin trials, see Microsoft Edge Origin Trials.

Name Description Register
Soft navigation heuristics Exposes soft-navigation heuristics for collecting performance metrics in single-page apps. Register
URL and eval hashes in CSP script-src Introduces url- and eval- hashes for script-src CSP directives, replacing hostname-based allowlists and unsafe-eval. Register
Web Install API Allows a website to install another website as a web app by using navigator.install(). Register
OpaqueRange Enables creating live ranges over text inside <input> and <textarea> elements that automatically update as the user edits. These ranges support geometry methods such as getBoundingClientRect() and the CSS Custom Highlight API, which enables use cases such as caret-positioned popups and inline spell-check highlighting directly on form controls, without cloning elements or exposing internal DOM structure. Register
Digital Credentials API - Issuance Support Triggers issuance of user credentials from a credential issuer server to a digital wallet application. Register
prerender_until_script Speculation Rules API action A Speculation Rules API action that prerenders a page but switches to prefetching when a script executes. Register
CPU Performance API Exposes information about the user's device capabilities, for use with the Compute Pressure API. Register
Connection allowlists Restricts connections from a document or worker to a server-distributed allowlist of endpoints. Register
focus-without-user-activation permissions policy Gives an embedder control over programmatic focus from embedded content via the focus-without-user-activation permissions policy. When the policy is denied for a frame, programmatic focus calls (element.focus(), autofocus, window.focus(), dialog.showModal(), and popover focusing) are blocked unless triggered by user activation, or focus is being delegated. Register
Enhanced Canvas TextMetrics Expands the TextMetrics Canvas API with selection rectangles, bounding-box queries, and glyph-cluster operations. Register
WebAudio Configurable Render Quantum Lets you specify a custom render quantum size when creating an AudioContext or OfflineAudioContext. Register
Prerendering cross-origin iframes Prerenders cross-origin iframes via an opt-in response header, instead of delaying them until page activation. Register
Container Timing Monitors when an annotated DOM container is displayed and has finished its initial paint. Register
Separate style and layout durations in the Long Animation Frame API Adds styleDuration, forcedStyleDuration, layoutDuration, and forcedLayoutDuration properties for deeper CSS performance analysis. Register
Prompt API sampling parameters The topK and temperature sampling parameters let you optimize model behavior per language model session. Register
<install> HTML element Declaratively install other websites as web apps by using the <install> element. Register
Declarative CSS Module Scripts Shares declarative stylesheets with shadow roots, including declarative shadow roots, using inline style modules. Register
HTML in canvas Enables rendering HTML in canvas with new drawing methods and the paint event. Register
Gamepad raw input event Instead of relying on frequent polling via navigator.getGamepads(), web pages can listen for gamepadrawinputchanged events. These events are fired whenever changes are detected between input frames from the same device. Register
Autofill Event Detects when browser autofill updates form controls, for adapting custom UI and validation. Register
WebAssembly Custom Descriptors V2 Stores data associated with source-level types more efficiently, in custom descriptor objects. Register
Speculative Load measurement performance.speculations exposes data about used and unused preloads, prefetches, and prerenders. This helps you measure the effectiveness of speculative loading strategies and optimize performance-versus-cost tradeoffs. Register
WebMCP Enables your site to register tools for an in-browser agent to complete tasks on behalf of a user. Register
Email Verification Protocol Enables websites to verify email ownership by using cryptographic tokens that are issued by email providers. This reduces reliance on email one-time passcodes (OTPs), and streamlines sign-up, sign-in, and recovery flows. Register

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Portions of this page are modifications based on work created and shared by Chromium.org and used according to terms described in the Creative Commons Attribution 4.0 International License.

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