Today we are rolling out a new Windows 10 preview build with significant Internet Explorer interoperability updates. In line with our commitment to interoperability and compatibility, this update includes over 2000 fixes for interoperability issues, support for 20 new platform features, and our new architecture for advancing interoperability and compatibility. We’re excited to be sharing this work at such an early stage in our development process and we look forward to hearing your feedback. We’re also rolling out this preview build to users of our new RemoteIE service, available for Windows, Mac OS X, and other platforms.
Introducing the “living” Edge document mode
The cornerstone of this update to IE is the “Edge” mode platform—a new document mode designed with interoperability at its core. With this mode, we’re applying the highly successful interoperability strategy of Windows Phone 8.1 Update to Windows 10.
As we announced in August 2013, we are deprecating document modes as of IE11. With our latest platform updates, the need for legacy document modes is primarily limited to Enterprise legacy web apps. With new architectural changes, these legacy document modes will be isolated from changes in the “living” Edge mode, which will help to guarantee a much higher level of compatibility for customers who depend on those modes and help us move even faster on improvements in Edge. The next major version of IE will still honor document modes served by intranet sites, sites on the Compatibility View list, and when used with Enterprise Mode only.
Public Internet sites will be rendered with the new Edge mode platform (ignoring X-UA-Compatible). It is our goal that Edge is the “living” document mode from here out and no further document modes will be introduced going forward. We need your help in testing this new mode so we are enabling it on by default for a small percentage of the Windows Insider user base and those of you that manually select the mode (see below).
Edge mode introduces an interoperable UA string designed to get today’s modern Web content, and to avoid old IE-only content. We’ve also spent a lot of time ensuring that the IE platform behaves like modern Web content expects.
In cases where these changes necessarily differ from standards, we’re following through with standards bodies and other browsers to update specs and implementations to reflect the interoperable behavior.
New features in preview
Also in Edge mode are early implementations of several in development features (we’ll blog more about these in depth soon):
CSS Preserve-3D – A popular developer request, this feature enables CSS transforms on multiple elements to be composed as a part of a 3D scene rather than flattened together.
Content Security Policy 1.0 – CSP is the next step forward since HTML5 Sandbox in preventing cross-site scripting. Pages provide a policy via the Content-Security-Policy header. This policy defines the origins from which resources on the page (JS, CSS, plugins, images, etc) are allowed to be loaded. This adds a defense-in-depth mechanism for preventing malicious content from being injected into the page. Resources blocked by CSP are reported through F12 tools and, optionally, as a report back to the server.
CSS Interaction Media Queries (Level 4) – A key component in responsive design is responsive input handling. We’ve talked before about adapting UX for input types, and this feature gives Web developers a new tool to do just that. Stylesheets can now use pointer and hover media queries to adapt UI based on the general precision of the user’s input (fine/coarse) and whether the device supports hover.
Selection API– We’ve improved our interoperability for the Selection object by implementing APIs like Selection.extend(), containsNode(),and setBaseAndExtent(). We have also helped get the W3C Selection API specification to First Public Working Draft and ensured it covers all of these interoperable APIs.
ECMAScript 6 Features – New language features from the latest ES6 “Harmony” draft specification:
Classes – syntax for declaring classes in ES6.
Promises – allows easier and cleaner asynchronous coding. Adds the Promise constructor, along with the ‘all’ and ‘race’ utility methods to the language itself.
Iterators – enables iteration over iterable objects (including arrays, array-like objects, iterators and generators), invoking a custom iteration hook with statements to be executed for the value of each distinct property.
Arrow Function – the arrow (=>) provides a shorthand for the function keyword with lexical ‘this’ binding.
Object Literal Enhancements – adds computed properties, concise method definitions, and short-hand for properties whose value is initialized to a same-named variable.
Spread – the spread operator expands iterable expressions into individual arguments. For example, a.b(…array) is roughly the same as a.b.apply(a, array).
Template Strings – string literals that allow for expressions to be evaluated and concatenated with the string literal.
Symbols – allows properties to be added to existing objects without the possibility of interference with the existing properties, unintended visibility, or with other uncoordinated additions by any other code.
Weak Set – a set of objects such that those objects will be collected if they are not referenced anywhere else.
Also in this release is the introduction of a new experimental features dashboard, accessed by browsing to about:flags. Here you’ll find new platform experiments that you can enable to try out the very bleeding edge of what we’re working on. Future experiments may include new standards we’re working on, interoperability fixes we’re trying out, new performance or security architectures, and more.
Given the sheer volume of changes in Edge mode, we’re going to progressively roll out the new mode by choosing a random set of Windows Insiders to get Edge while the rest remain in 11 document mode. Our data science and quality engineering teams will leverage user feedback and anonymous telemetry to guide the roll out while we make tweaks to the platform in future preview builds accordingly.
If you’re a developer coding against new features or testing for compatibility, you can head over to about:flags and choose Edge mode explicitly by setting “Enable Experimental Web Platform Features” to “Enabled” (“Automatic” restores you to the default roll out and “Disabled” lets you compare with 11 mode).
At any time, developers can identify the mode a page is in via F12 tools. Note that dynamically switching between Edge and other document modes from F12 isn’t yet supported (we told you these experiments may bite!). For now, use about:flags for switching when developing and testing.
We’re sharing our changes earlier in the process than ever so we can collect your feedback to help shape the product. Last month, we introduced the IE Platform Suggestion Box on UserVoice where developers can suggest and vote on improvements to the platform. In this release, we’re adding a feedback tool right in the top-level UI. Just click the smiley face icon to “send a frown” such as reporting a problem on a site. If the page is running in Edge mode, you can also try reloading in the “compatibility mode” (IE11 behavior). As always, you can also report issues through Connect or the Windows Feedback app in the Windows 10 Tech Preview.
We’re excited to share with you an early look at what we’ve been working on. Join our engineering team on Twitter at 11am PST Friday November 14 where we’ll be answering your #AskIE questions, and follow along with some of the other work we’re planning at status.modern.IE.
Jacob Rossi (@jacobrossi) – Senior Program Manager, Internet Explorer
Update 11/12/2014 : Added ES6 Proxies and WeakSet to the list of features in this preview build, removed RegExp built-ins (still in development)