Optimize JS is an experimental JavaScript transformation tool created to reduce initial parsing and execution time in older browser engines. It parses JavaScript into a syntax tree and identifies functions that are immediately invoked or likely to execute eagerly. Those functions are wrapped in parentheses so engines such as older V8 versions can avoid unnecessary lazy preparsing. The tool can operate from the command line or through a JavaScript API and can optionally generate source maps. Plugins were also created for Grunt, Gulp, and webpack workflows. Historical benchmarks showed improvements in several older browsers, but results varied significantly by engine and workload. The project is unmaintained, and its author and the V8 team now advise against assuming the technique benefits modern browsers.
Features
- AST-based JavaScript transformation
- IIFE and eager-function detection
- Parenthesis-based parsing optimization
- Command-line and JavaScript APIs
- Optional source map generation
- Grunt, Gulp, and webpack plugin integrations