SCSS Compiler NodeJS

var gulp    = require('gulp');
var sass    = require('gulp-sass');
var rename  = require('gulp-rename');
var prefix  = require('gulp-autoprefixer');
var minCss  = require('gulp-minify-css');

gulp.task('build', function () {
  return gulp.src('public/sass/**/*.scss')
    .pipe(sass({
      onError: sass.logError,
      outputStyle: 'expanded',
    }))

    .pipe(minCss())
    .pipe(rename({
      suffix: '.min'
    }))
    
    .pipe(gulp.dest('public/css'));
});

gulp.task('watch', function(){
  return gulp.watch('public/sass/**/*.scss', gulp.series('build'));
});