UglifyJS does not currently support EcmaScript 6 structures like classes.
You’ll probably need to run your JavaScript through a transpiler step first, or find a minifier that knows what to do with ES6 code.
Update 2017-06-17
The branch of UglifyJS that is designed to work with ES6 is now published as uglify-es
on npm.
Update 2018-09-10
terser
is the new uglify-es
, uglify-es
is no longer maintained.
If using gulp both npmjs gulp-uglify-es and npmjs gulp-terser packages support terser.
npm install gulp-terser --save-dev
const gulp = require('gulp');
const terser = require('gulp-terser');
function es(){
return gulp.src('./src/index.js')
.pipe(terser())
.pipe(gulp.dest('./build'))
}
gulp.task('default', es);