Chakra (JavaScript engine)

Chakra (JavaScript engine)
Name	Chakra
Developer	Microsoft
Released	2015
Latest release	2019
Programming language	C++
Operating system	Windows, Linux
Genre	JavaScript engine
License	MIT (parts)

Chakra (JavaScript engine) is a JavaScript engine developed by Microsoft initially for the Internet Explorer 9 era and later for Microsoft Edge to implement ECMAScript standards and provide a runtime for Active Scripting hosts. Designed to interoperate with Windows 10, Visual Studio, and server environments such as Node.js, it pursued high throughput for web applications and host integration with COM and WinRT.

Overview

Chakra was created by teams at Microsoft working alongside projects like Internet Explorer, EdgeHTML, and tooling in Visual Studio to support ECMAScript 2015 and subsequent specifications. It was positioned against contemporaries such as V8, SpiderMonkey, and JavaScriptCore to power web browsers, server runtimes, and embedded scenarios in Windows 10 and cloud services like Azure. Chakra combined a JIT compiler, garbage collector, and runtime API intended for embedding by applications including Microsoft Office, Skype, and platform features in Xbox One.

History and Development

Development traces to engineering groups responsible for Internet Explorer 9 and later the EdgeHTML rendering engine; leadership included program managers and architects who had worked on IE and browser interoperability initiatives. Major milestones aligned with releases of Windows 10, the original Edge browser, and cross-platform initiatives announced around Microsoft Build. In 2016–2018, Microsoft open-sourced parts and later released an experimental port to Node.js integration and a separate effort to port to Linux and macOS. The project interacted with standards bodies such as Ecma International and was discussed at conferences like Microsoft Ignite and Build.

Architecture and Features

Chakra's architecture comprised a multi-stage JIT compiler, an optimizing engine, an interpreter, and a garbage collector tuned for desktop and server workloads. The engine exposed hosting APIs similar to those used by Active Scripting hosts and WinRT components to allow integration with applications like Microsoft Office and Visual Studio Code. Features implemented targeted ECMAScript editions and included Typed Arrays support used by WebGL, asm.js compatibility, and interop primitives for COM and Windows Runtime. Chakra's garbage collector and JIT design drew comparisons with V8's Turbofan, SpiderMonkey's IonMonkey, and JavaScriptCore's FTL to balance startup latency and long-running throughput.

Performance and Benchmarks

Performance evaluations compared Chakra against V8, SpiderMonkey, and JavaScriptCore across benchmarks like Octane, JetStream, and Kraken. Microsoft published internal and third-party analyses showing competitive throughput on Windows 10 devices and specific scenarios such as single-page applications used by Outlook.com, OneDrive, and enterprise portals. Independent testing at events like SPEC workshops and community benchmarks by contributors to Node.js and Electron highlighted strengths in JIT warm-up, startup latency for command-line tools, and garbage collection behavior vs. engines used by Google Chrome and Firefox.

Platform Integration and Embedding

Chakra was embedded in Microsoft products ranging from Internet Explorer-era hosts to Edge and system components within Windows 10. It offered hosting APIs adopted by Visual Studio, Skype, and server integrations in Azure services for script execution and automation. Third-party projects explored embedding Chakra into runtimes such as Node.js-based tooling and desktop frameworks like Electron, while cross-platform ports enabled use in Linux and macOS environments promoted at GitHub demonstrations and community meetings.

Security and Compatibility

Security updates for Chakra were coordinated with Microsoft Security Response Center release cycles alongside Windows Update patches and browser security advisories issued for EdgeHTML and Internet Explorer. Microsoft engaged with vulnerability disclosure programs run by organizations like CERT and vendors such as Google and Mozilla during coordinated vulnerability disclosure processes. Compatibility shims and standards compliance efforts were pursued with Ecma International and web compatibility testing platforms like Web Platform Tests to address interoperability with content from sites such as Wikipedia, YouTube, and enterprise web applications.

Legacy and Successors

Following a strategic shift toward Chromium and the adoption of V8 in the new Edge (Chromium) browser, Chakra's in-browser role diminished while parts were open-sourced and integrated into community projects hosted on GitHub. Successor efforts and related projects include ChakraCore forks, community-maintained ports, and explorations of runtime embedding for serverless and IoT scenarios connected to Azure IoT and Azure Functions. The transition influenced Microsoft's contributions to Chromium and collaboration with organizations such as Google and The Linux Foundation.

Category:JavaScript engines Category:Microsoft software