gulpfile.js

const {src, dest, watch, series} = require('gulp');
const sass = require('gulp-sass')(require('sass'));
const prefix = require('gulp-autoprefixer');
const minify = require('gulp-clean-css');
const terser = require('gulp-terser');
const rename = require('gulp-rename');
const concat = require('gulp-concat');

function compilerSass ()
{
    return src('styles/main.scss')
        .pipe(sass())
        .pipe(prefix())
        .pipe(minify())
        .pipe(rename('style.min.css'))
        .pipe(dest('dist/css'));
}

function jsMin()
{
    return src('scripts/main.js')
        .pipe(terser())
        .pipe(rename('main.min.js'))
        .pipe(dest('scripts'));
}

function jsBundle()
{
    return src([
            'scripts/jquery.min.js',
            'scripts/main.min.js',
        ])
        .pipe(concat('script.min.js'))
        .pipe(dest('dist/js'));
}

function watchTask()
{
    watch('styles/**/*.scss', compilerSass);
    watch('scripts/main.js', jsMin);
    watch('scripts/main.min.js', jsBundle);
}

exports.default = series(
    compilerSass,
    jsMin,
    jsBundle,
    watchTask
);

exports.build = series(
    compilerSass,
    jsMin,
    jsBundle
);