Gulp Watch Scss Changes And Minify

gulpfile.js

/* You should install with npm below packages to your project 
    "gulp": "^4.0.2",
    "gulp-sass": "^4.1.0",
    "gulp-scss": "^1.4.0"
*/
var gulp = require('gulp');
var sass = require('gulp-sass');


gulp.task('listen',function () {
    return gulp.src('./scss/main.scss')
    .pipe(sass({outputStyle: 'compressed'}))
    .pipe(gulp.dest('./'))
});

gulp.task('watch',function () {
    gulp.watch('./scss/**/*.scss',gulp.series('listen'))
});