index.js
function uglify(options = {}) {
    return {
        name: 'uglify',

        renderChunk(code) {
            options.sourceMap = true;
            return minify(code, options);
        }
    };
}
function uglify(options = {}) {
    return {
        name: 'uglify',

        renderChunk(code) {
            options.sourceMap = true;
            return minify(code, options);
        }
    };
}
function uglify ( options = { } ) { return { name : 'uglify' , renderChunk ( code ) { options . sourceMap = true ; return minify ( code , options ) ; } } ; }
minify after tree shaking
minify after tree shaking