oliverbooth.dev/Gulpfile.js

const gulp = require("gulp");
const fs = require("fs");
const sass = require('gulp-sass')(require("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 path = require("path");
const named = require("vinyl-named");

const srcDir = "src";
const destDir = "OliverBooth/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(done) {
    const tasks = fs.readdirSync("tmp/js", {withFileTypes: true})
        .filter(dirent => dirent.isDirectory())
        .map(d => bundleDir(d.name));
    return gulp.parallel(...tasks)(done);

    function bundleDir(directory) {
        return () => gulp.src(`tmp/js/${directory}/${directory}.js`)
            .pipe(webpack({mode: "production", output: {filename: `${directory}.min.js`}}))
            .pipe(gulp.dest(`${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);