JSC 💕 ES6

Update: The previous version of this post showed performance data from ARES-6 version 1.0.

WebKit now supports the prefers-reduced-motion media feature, part of CSS Media Queries Level 5, User Preferences.

WebKit fully supports the ECMA-402 API for internationalization in JavaScript to adapt data presentation to fit a user’s language and country

As of r202125, JavaScriptCore supports all of the new features in the ECMAScript 6 (ES6) language specification.

JavaScriptCore has a new sampling profiler that powers Web Inspector’s JavaScript & Events timeline.

Web Inspector now includes two new timelines for debugging a webpage’s memory usage.

JavaScriptCore CSI:
A Crash Site Investigation Story

When debugging JavaScript bugs, web developers have Web Inspector which provides a debugger and many introspective tools to examine their code with.

Proper Tail Calls (PTC) is a new feature in the ECMAScript 6 language.

WebKit’s FTL JIT now uses a new backend on OS X — the Bare Bones Backend, or B3 for short, replaces LLVM as the low-level optimizer.

In Safari 9 for OS X and iOS 9 you’ll be able to use some great ES6 features — there are even more you can try out if you run the nightly build.

JavaScript Type and Code Coverage Profiling

Web Inspector now has two great tools designed to make debugging JavaScript programs easier: the Code Coverage Profiler and the Type Profiler.

Designed to bring aggressive C-like optimizations to the largest variety of JavaScript programs.