TL;DR

Rspack now supports import.meta.glob (a file-system import API) and enforces stricter rules for React Server Components (RSC) to prevent invalid imports between server and client bundles.

New

• import.meta.glob Support: Enables a familiar import pattern for file-based assets, aligning with Vite and Turbopack.
• RSC Validation: Rspack validates server-only and client-only module boundaries, preventing incorrect imports between server and client code.
• Deterministic Module IDs: A plugin is now available to control module IDs for improved long-term caching.

Fixes Worth Knowing

• CSS Modules now preserve the original order of composes declarations, resolving potential specificity issues.
• Fixes to ESM library support improve runtime chunk splitting and external type resolution.
• Watcher improvements address startup race conditions and persistent mtime baselines.

Before You Upgrade

If you are using React Server Components, review your imports to ensure compliance with the new server-only and client-only marker package rules.

TL;DR

Rspack v2.0.0-rc.3 significantly improves build performance with a persistent SWC cache and optimizations to code splitting and tracing.

Breaking

• Browser Crate Removal: The rspack_browser crate is removed; projects must now use @rspack/browser within a Worker (separate process) for browser builds.

New

• JSONP Template Plugin: Exposes a plugin for JSONP (JavaScript Object Notation with Padding) template generation.
• Relative Output Paths: Output paths can now be specified relative to the project context.
• Enforce Size Threshold: enforceSizeThreshold option added to split-chunks for more control over code splitting.

Fixes Worth Knowing

• CJS Tree Shaking: Corrected tree shaking for CommonJS (CJS) exports.
• Wasm Build Stability: Resolved flakiness in WebAssembly (Wasm) builds, particularly in browser environments.
• Module Externals: Improved handling of module external definitions, supporting array types.

Before You Upgrade

• If you are using the @rspack/browser crate directly, migrate to using it within a Worker. See documentation for details.

TL;DR

Rspack now supports more complex comment extraction patterns and array share scopes for module federation, improving flexibility for advanced use cases.

New

• Module Federation: Array share scopes are now supported, enabling more dynamic and configurable shared module setups.
• Comment Extraction: Regex flags and JavaScript lookaheads are now supported in extractComments conditions, allowing for more precise comment targeting.

Fixes Worth Knowing

• Fixed an issue where WorkerPlugin wasn’t correctly inherited in child compilers, ensuring worker threads function as expected.

TL;DR

Rspack v1.7.0 introduces significant performance improvements by upgrading to SWC v50 and enables lazy compilation by default for dynamic imports, speeding up build times.

Breaking

• Experiments API Changes: The experiments.inlineConst, experiments.inlineEnum, and experiments.lazyBarrel options are now stable and have moved from the experiments object to the module.parser.javascript and optimization objects in your configuration.

New

• Asset Module Support: Added support for type: 'text' in asset modules, allowing for more flexible handling of different asset types.
• Universal Chunk Loading: Implemented UniversalCompileAsyncWasmPlugin for improved loading of asynchronous chunks.

Fixes Worth Knowing

• Fixed issues with relative resource paths on Windows in source maps.
• Resolved problems with Wasm plugin panics when using persistent caching.
• Improved handling of ignored asset modules and data URL exports.
• Corrected issues with ignoreWarnings and improved documentation.

Before You Upgrade

• Update your configuration to reflect the changes to the experimental features, moving them from experiments to module.parser.javascript and optimization.

TL;DR

Rspack now includes a new, opt-in CSS minimizer powered by Lightning CSS (a fast CSS compiler), offering improved CSS tree shaking and the potential to remove PostCSS (CSS processing tool) for downgrading.

New

• LightningCSS Minimizer: A new CSS minimizer is available for faster CSS processing and tree shaking.
• Worker Loader Compatibility: Added temporary compatibility for projects using worker-loader (for handling web workers).

Fixes Worth Knowing

• Fixed issues with CSS modules incorrectly composing class names.
• Resolved a segmentation fault with custom loaders.
• Improved handling of URL dependencies in minimized CSS.
• Corrected source map generation issues.

Before You Upgrade

If you are currently using PostCSS solely for browser downgrading, you may be able to remove it after enabling the LightningCSS minimizer.

TL;DR

Rspack v0.7.0 introduces significant performance improvements and new features like lazy compilation, while also deprecating older APIs in preparation for future development.

Breaking

• Compiler and MultiCompiler APIs are deprecated. (These are core Rspack interfaces, requiring code updates for users directly interacting with them.)
• Compilation API is deprecated. (Similar to the above, this impacts advanced users extending Rspack’s compilation process.)
• SWC has been updated. (May require adjustments if relying on specific SWC behavior.)

New

• Lazy compilation is now supported. (Improves startup time for larger projects by deferring compilation of modules.)
• Inline entry modules are supported. (Can reduce bundle size and improve performance.)
• Performance configuration options are available. (Allows users to fine-tune Rspack’s performance characteristics.)

Fixes Worth Knowing

• Fixed issues with Module Federation runtime and data URIs. (Addresses compatibility and functionality for projects using Module Federation.)
• Corrected code splitting to be deterministic. (Ensures consistent build outputs.)
• Fixed memory leaks related to dependencies. (Improves stability and resource usage.)

Before You Upgrade

• Review your code for usage of the deprecated Compiler, MultiCompiler, and Compilation APIs and plan for migration to newer alternatives.
• Test thoroughly after updating SWC to ensure compatibility with your existing configuration.