Microsoft's ChakraCore adds WebAssembly support

Version 1.4 of the JavaScript engine core adds experimental support for the WebAssembly portable code format

ChakraCore, the open source core of the JavaScript engine powering Microsoft's Edge browser, has been upgraded with experimental support for the WebAssembly portable code format for browsers and cross-platform JIT compilation capabilities.

WebAssembly, which has been backed by browser vendors like Google, Microsoft, Mozilla, and Apple, is a highly touted portable bytecode technology intended to improve web performance.

The upgrade, known as version 1.4.0, also adds JIT support on Linux and MacOS, and out-of-process JIT support for Edge. This change adds support for hosts to optionally supply Chakra with an external process to act as a JIT server, which can support the running of any number of Chakra runtime clients.

Described as a "minor release" by a Microsoft representative, ChakraCore 1.4.0 also enables async functions by default and enhances time-travel debugging, which allows developers to look at faulting code within the full fidelity of the debugger with runtime context preserved. It works on a record-and-playback principle, with the record mode creating a trace file during execution that can then be played back.

For memory reduction, version 1.4.0 leverages function body redeferral. This covers redefer function bodies that are not currently being executed and are eligible for deferred parsing, Microsoft said.

JSRT (JavaScript Runtime) String APIs have been updated but are in an experimental phase; ChakraCore backs JSRT APIs for embedding ChakraCore in Applications. Version 1.4.0, also enables ShareArrayBuffer, once again under and experimental flag.

Copyright © 2016 IDG Communications, Inc.

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