● Covered by 1 source · 1 reportMedium impact1 neutral
Bun 1.4 Released with Increased Node.js Compatibility and Performance Improvements
Key points
- Added +1,517 Node.js test suite compatibility tests.
- Fixed over 2,900 issues and introduced new APIs.
- Reduced idle CPU usage by 5x and memory usage by up to 35%.
- Improved startup time by 50% on Linux.
- Rewrote Bun from Zig to Rust.
Enhanced Node.js Compatibility
Bun 1.4 significantly improves its compatibility with Node.js by incorporating an additional 1,517 tests from the Node.js test suite. This update means that core Node.js modules like `node:http`, `node:fs`, and `node:cluster` now pass 97% of Node's own tests, with others like `node:events` reaching 100% compatibility. This ongoing effort aims to make Bun a more seamless drop-in replacement for Node.js environments.
Performance Optimizations
The latest release brings notable performance gains. Bun 1.4 reduces idle CPU usage by a factor of five and decreases memory consumption by up to 35%. Additionally, the startup time on Linux systems has been improved by 50%. These optimizations contribute to a more efficient runtime for JavaScript and TypeScript applications.
New Features and API Additions
Bun 1.4 introduces several new APIs and functionalities, including `Bun.Image`, `Bun.WebView`, `Bun.markdown`, `Bun.cron()`, and `Bun.Terminal`. Command-line tools have also been expanded with `bun run --parallel`, `bun test --parallel`, `bun audit fix`, `bun dedupe`, and `bun prune`. These additions provide developers with more built-in capabilities within the Bun toolkit.
Underlying Technology Shift
A significant change in Bun 1.4 is the complete rewrite of its core from Zig to Rust. This foundational shift in the programming language used for Bun's implementation may impact future development, stability, and performance characteristics of the runtime.
Ecosystem Integration
The update also enhances Bun's ability to run existing JavaScript ecosystem tools. Playwright now functions on Bun, supporting features like `connectOverCDP()` and `playwright test`. Next.js 16.3 with Turbopack and the React Compiler now works with `bun --bun next build`, and Vitest runs under Bun, including coverage and thread/fork pools. Compatibility with various packages such as Nuxt, Testcontainers, and OpenTelemetry has also been improved.
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Primary sources
GitHub oven-sh/bun GitHub tc39/proposal-decorators GitHub evanw/decorator-tests GitHub zlib-ng/zlib-ng GitHub toml-lang/toml-test npm @datadog/pprofReporting from
Bun 1.4 has been released, adding over 1,500 Node.js test suite compatibility improvements, fixing more than 2,900 issues, and introducing new APIs. The update also includes performance enhancements such as reduced CPU and memory usage, and faster startup times on Linux.