OXC

Minifier ​

JavaScript minification plays a crucial role in optimizing website performance as it reduces the amount of data sent to users, resulting in faster page loads. This holds tremendous economic value, particularly for e-commerce websites, where every second can equate to millions of dollars.

However, existing minifiers typically require a trade-off between compression quality and speed. You have to choose between the slowest for the best compression or the fastest for less compression. But what if we could develop a faster minifier without compromising on compression?

Project Goals ​

We are actively working on a prototype that aims to achieve this goal, by porting all test cases from well-known minifiers such as google-closure-compiler, terser, esbuild, and tdewolff-minify.

Preliminary results indicate that we are on track to achieve our objectives. With the Oxc minifier, you can expect faster minification times without sacrificing compression quality.

Target Performance ​

  • Speed: faster than Terser, competitive with esbuild
  • Compression: Match or exceed Terser's compression ratio
  • Correctness: Pass all major minifier test suites

Architecture Overview ​

Design Principles ​

The Oxc minifier is built around several key principles:

  1. Semantic-Aware: Uses semantic analysis to enable safe optimizations
  2. Incremental: Designed for incremental compilation workflows
  3. Configurable: Supports various optimization levels and targets
  4. Correct: Prioritizes correctness over aggressive optimization

Current Status ​

Implemented Features ​

  • ✅ Dead Code Elimination: Remove unreachable code
  • ✅ Constant Folding: Evaluate constant expressions
  • ✅ Tree Shaking: Remove unused exports (basic)
  • ✅ Variable Merging: Merge variable declarations
  • ✅ Statement Merging: Combine compatible statements
  • ✅ Name Mangling: Shorten variable and function names
  • ✅ Control Flow Optimization: Simplify control structures
  • ✅ Function Inlining: Inline small functions
  • ✅ Advanced Tree Shaking: Cross-module optimization

Performance Optimization ​

Key strategies for maintaining performance:

  1. Minimal AST Traversals: Combine multiple optimizations in single passes
  2. Efficient Data Structures: Use arena allocation and compact representations
  3. Early Termination: Skip optimizations when no benefit is possible

Resources ​

Documentation ​

External References ​

Playgrounds ​

© 2025 VoidZero Inc. and Oxc contributors.