Highlights of V8 7.0 Release: Embedded Built‑ins, WebAssembly Threads, New JavaScript Features, and API Changes
V8 7.0, released on October 15, introduces memory‑saving Embedded built‑ins across platforms, preview support for WebAssembly threads via chrome://flags, new JavaScript features such as Symbol.prototype.description and a stable Array.prototype.sort using TimSort, plus API changes accessible through git logs and checkout commands.
The V8 team creates a new V8 release branch every six weeks, branching from the master of V8's Git repository before a Chrome Beta milestone.
On October 15, the V8 team announced the official release of V8 7.0. This version will be shipped together with the stable Chrome 70 in a few weeks, having been available as a Beta for integration testing. V8 7.0 brings many developer‑friendly new features, highlighted below.
Embedded built‑ins
Embedded built‑ins share generated code between multiple V8 isolates to save memory. Since V6.9, this capability has been enabled on x64; V7.0 expands it to all platforms except ia32, further reducing memory usage.
WebAssembly thread preview
WebAssembly (Wasm) enables code written in C++ and other languages to run on the web. Native applications benefit from threading for parallel computation, and most C/C++ developers are familiar with pthreads as the standard thread API.
The WebAssembly Community Group has been working to bring true multithreading to the web. As part of this effort, V8 now provides the necessary support for threads in the WebAssembly engine. To use this feature in Chrome, enable it via chrome://flags/#enable-webassembly-threads or register an Origin Trial for your site, allowing developers to experiment with the feature before it is fully standardized.
Origin Trial: https://github.com/GoogleChrome/OriginTrials
New JavaScript language features
Added Symbol.prototype.description , making it easier to retrieve a Symbol’s description directly. Previously, developers had to access the description indirectly via Symbol.prototype.toString() . Thanks to Igalia for contributing this implementation.
Array.prototype.sort is now stable in V7.0, using the TimSort algorithm instead of the previous unstable quicksort for arrays larger than ten elements. For more details, see the blog post linked below.
Blog post: https://v8.dev/blog/array-sort
V8 API
To view the list of API changes, run: git log branch-heads/6.9..branch-heads/7.0 include/v8.h
Developers who have already checked out the V8 source can test the new features with: git checkout -b 7.0 -t branch-heads/7.0
Original English article: https://v8.dev/blog/v8-release-70
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