UglifyJS2

UglifyJS2 is a JavaScript code minifier and compressor that is part of the UglifyJS project. It processes JavaScript source code to remove whitespace, shorten identifiers, and apply various optimizations in order to reduce file size for distribution. The tool comprises a compressor, a mangler, and an AST-based pipeline for parsing, transforming, and code generation.

UglifyJS2 was developed as a rewrite of the original UglifyJS to provide improved support for newer JavaScript syntax (such as ES2015 and beyond) and a more robust set of optimization features. It is distributed as a command-line tool and can also be used programmatically through an API, making it suitable for integration into build pipelines and task runners.

Key features include dead code elimination, function inlining, constant folding, and scope-aware name mangling. It supports generating source maps, options to drop console statements, and configurable compression and mangling behavior. UglifyJS2 can also handle modules and offers a range of flags to tailor output for compatibility with different environments.

Typical usage involves the command line, for example: uglifyjs input.js -o output.min.js -c -m. Programmatic use uses the UglifyJS.minify function to perform compression and mangling with a configuration object, such as { compress: true, mangle: true }. In recent years, development for UglifyJS2 has been complemented by forks that extend ES2015+ support, with Terser becoming a commonly used alternative in modern toolchains.