Butternut

Butternut is an experimental ES2015-aware JavaScript minifier that uses a novel approach: instead of manipulating an AST, it edits code in place using magic-string, resulting in significantly faster minification. It is typically 3x faster than UglifyJS and 10-15x faster than Babili. However, it is alpha software (v0.4.6) and should be thoroughly tested before production use. It supports the check option to parse output for correctness. Note: the package is deprecated; users are advised to migrate to modern minifiers like terser or uglify-es.