oliverbooth.dev/Gulpfile.js

const gulp = require('gulp');
const sass = require('gulp-sass')(require('node-sass'));
const cleanCSS = require('gulp-clean-css');
const rename = require('gulp-rename');
const ts = require('gulp-typescript');
const terser = require('gulp-terser');
const webpack = require('webpack-stream');

const srcDir = 'src';
const destDir = 'OliverBooth.Common/wwwroot';

function compileSCSS() {
    return gulp.src(`${srcDir}/scss/**/*.scss`)
        .pipe(sass().on('error', sass.logError))
        .pipe(cleanCSS({ compatibility: 'ie11' }))
        .pipe(rename({ suffix: '.min' }))
        .pipe(gulp.dest(`${destDir}/css`));
}

function compileTS() {
    return gulp.src(`${srcDir}/ts/**/*.ts`)
        .pipe(ts("tsconfig.json"))
        .pipe(terser())
        .pipe(gulp.dest(`tmp/js`));
}

function bundleJS() {
    return gulp.src('tmp/js/*.js')
        .pipe(webpack({ mode: 'production', output: { filename: 'app.min.js' } }))
        .pipe(gulp.dest(`${destDir}/js`));
}

function copyJS() {
    return gulp.src(`${srcDir}/ts/**/*.js`)
        .pipe(rename({ suffix: '.min' }))
        .pipe(gulp.dest(`${destDir}/js`));
}

function copyCSS() {
    return gulp.src(`${srcDir}/scss/**/*.css`)
        .pipe(rename({ suffix: '.min' }))
        .pipe(gulp.dest(`${destDir}/css`));
}

function copyImages() {
    return gulp.src(`${srcDir}/img/**/*.*`)
        .pipe(gulp.dest(`${destDir}/img`));
}

exports.default = compileSCSS;
exports.default = gulp.parallel(compileSCSS, gulp.series(compileTS, bundleJS), copyCSS, copyJS, copyImages);