gulpfile.js

const { parallel, watch } = require("gulp");

// Pull in each task
const images = require("./gulp-tasks/images.js");
const sass = require("./gulp-tasks/sass.js");
const criticalScripts = require("./gulp-tasks/critical-scripts.js");
const inlineScripts = require("./gulp-tasks/inline-scripts.js");

// Set each directory and contents that we want to watch and
// assign the relevant task. `ignoreInitial` set to true will
// prevent the task being run when we run `gulp watch`, but it
// will run when a file changes.
const watcher = () => {
    watch("./src/images/**/*", { ignoreInitial: true }, images);
    watch("./src/scss/**/*.scss", { ignoreInitial: true }, sass);
    watch("./src/js/critical/**/*.js", { ignoreInitial: true }, criticalScripts);
    watch("./src/js/*.js", { ignoreInitial: true }, inlineScripts);
};

// The default (if someone just runs `gulp`) is to run each task in parallel
exports.default = parallel(images, sass, criticalScripts, inlineScripts);

// This is our watcher task that instructs gulp to watch directories and
// act accordingly
exports.watch = watcher;