Google’s V8 JavaScript Engine Version 7 Now Available, Here’s What’s New

Google has recently released an update to their open source JavaScript and WebAssembly engine for the Chrome browser, V8, with beta V8 Version 7.4. This version adds the potential to expand the the engines footprint to platforms such as Apple iOS or possibly MacOS.

Here’s whats new in Google’s beta V8 Version 7.4:

• JIT-less V8, in which JavaScript execution is supported without allocating executable memory at runtime. This could allow expansion of V8 onto platforms such as Apple iOS, smart TVs, and game consoles. The default configuration of V8 has relied on the ability to allocate and modify executable memory at runtime. But there are situations where it can be desirable to run the engine without allocating executable memory, such as platforms that have prohibited write access to nonexecutable memory for nonprivileged applications, including iOS. Also, disallowing writes to executable memory reduces the attack surface of the application for exploits. With the JIT-less mode, V8 switches to an interpreter-only mode for JavaScript; WebAssembly currently does not support this mode. JIT-less mode does come with a performance penalty, however.
• WebAssembly Threads/Atomics are now enabled on non-Android OSes. This move unlocks the use of multiple cores via WebAssembly, enabling new, computation-heavy uses on the web.
• To improve performance, Version 7.4 skips arguments adaption in some cases, reducing call overhead by 60 percent.
• Performance has been improved for calling into native accessors, which are DOM accessors.
• Preparser performance was improved by removing a deduplication involving property names. Additionally, a performance issue was fixed that involved custom UTF-8 decoding used by the source stream.
• To reduce memory overhead, support has been implemented for flushing compiled bytecode from functions during garbage collection if they have not been executed recently.
• To support private class fields, Developers can mark a field as private by prepending it with the # prefix.

The production version is set to arrive in April 2019, and you can the download the current production version of Google V8 from the Chromium V8 repo here.

Image Credit: Medium

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