gulpfile.js

const gulp =require('gulp');

const sass =require('gulp-sass');
const cssnano = require('gulp-cssnano');
const rev =require('gulp-rev');

const uglify = require('gulp-uglify-es').default;

const imagemin = require('gulp-imagemin');

const del = require('del');

gulp.task('css',function(done){
    console.log('minifying css');
    //minification
    gulp.src('./assests/sass/**/*.scss')
    .pipe(sass())                         //pipe calls all the sub middlewares in gulp
    .pipe(cssnano())
    .pipe(gulp.dest('./assests.css'));
    // after minification changing file name convention form home.css to home-94jkj34j.css
    gulp.src('./assests/**/*.css')
    .pipe(rev())
    .pipe(gulp.dest('./public/assests'))
    .pipe(rev.manifest({
        cwd : 'public' ,
        merge : true
    }))
    .pipe(gulp.dest('./public/assests'));
    done();
})


gulp.task('js', function(done){
    console.log('minifying js...');
     gulp.src('./assests/**/*.js')
    .pipe(uglify())
    .pipe(rev())
    .pipe(gulp.dest('./public/assests'))
    .pipe(rev.manifest({
        cwd: 'public',
        merge: true
    }))
    .pipe(gulp.dest('./public/assests'));
    done()
});


gulp.task('images', function(done){
    console.log('compressing images...');
    gulp.src('./assests/**/*.+(png|jpg|gif|svg|jpeg)')
    .pipe(imagemin())
    .pipe(rev())
    .pipe(gulp.dest('./public/assests'))
    .pipe(rev.manifest({
        cwd: 'public',
        merge: true
    }))
    .pipe(gulp.dest('./public/assests'));
    done();
});


// empty the public/assets directory
gulp.task('clean:assests', function(done){
    del.sync('./public/assests');
    done();
});

//to run all the 4 tasks('clean:assests', 'css', 'js', 'images') in one command ("gulp build")
gulp.task('build', gulp.series('clean:assests', 'css', 'js', 'images'), function(done){
    console.log('Building assets');
    done();
});