How to add .watch to gulpfile.js - node.js

Question

I am using gulp for minify JS and CSS.
Everything works fine, but I need add .watch for automatic this process.
Anyone help me please?
Here is my code:
// Require the npm modules we need
var gulp = require("gulp"),
rename = require("gulp-rename"),
cleanCSS = require("gulp-clean-css"),
terser = require("gulp-terser");
// Looks for a file called styles.css inside the css directory
// Copies and renames the file to styles.min.css
// Minifies the CSS
// Saves the new file inside the css directory
function minifyCSS() {
return gulp.src("./_statika/css/style.css")
.pipe(rename("style.min.css"))
.pipe(cleanCSS())
.pipe(gulp.dest("./css"));
}
// Looks for a file called app.js inside the js directory
// Copies and renames the file to app.min.js
// Minifies the JS
// Saves the new file inside the js directory
function minifyJS() {
return gulp.src("./_statika/js/scripts.js")
.pipe(rename("scripts.min.js"))
.pipe(terser())
.pipe(gulp.dest("./js"));
}
// Makes both functions available as a single default task
// The two functions will execute asynchronously (in parallel)
// The task will run when you use the gulp command in the terminal
exports.default = gulp.parallel(minifyCSS, minifyJS);
Thanks a lot

Answer 1

Just try this:
gulp.watch("./_statika/css/style.css", minifyCSS);
gulp.watch("./_statika/js/scripts.js", minifyJS);