gulpfile.js

'use strict';

const gulp = require('gulp');
const uglify = require('gulp-uglify');
const babel = require('gulp-babel');
const autoprefixer = require('gulp-autoprefixer');
const cp = require('child_process');
const spawn = cp.spawn;
const browserSync = require('browser-sync');
const del = require('del');
const debug = require('gulp-debug');
const cssmin = require('gulp-cssmin');
const cleaner = require('gulp-clean');
const concat = require('gulp-concat');
const useref = require('gulp-useref');

const jekyll_command = process.platform === 'win32' ? 'jekyll.bat' : 'jekyll';
const messages = {
    jekyllBuild: '<span style="color: grey">Running:</span> $ jekyll build'
};

const jekyll_build = (done) => {
  browserSync.notify(messages.jekyllBuild)
  return spawn(jekyll_command, ['build'], {stdio:'inherit'}).on('close', done);
}


const clean = (done) => {
  console.log("Began clean");
  return del('_site');
  //return gulp.src('_site/', {read: false})
    //    .pipe(cleaner());
};

const clean_unneeded = (done) => {
  console.log("cleaning unnecessary files");
  return del(['_site/assets/js/*', '_site/assets/css/*', '!_site/assets/js/', '!_site/assets/css/', '!_site/assets/css/*.min.css', '!_site/assets/js/*.min.js']);
}
const useref_task = () =>{
  console.log("Began useref");
  return gulp.src('_site/*.html')
    .pipe(useref())
    .pipe(gulp.dest('_site/'));
};
const css = () => {
  console.log("Began css");
  return gulp.src('_assets/css/*.css')
    .pipe(debug())
    .pipe(autoprefixer())
    .pipe(cssmin())
    .pipe(gulp.dest('_site/assets/css'));
};
const fonts = () => {
  console.log("Began fonts");
  return gulp.src('_assets/fonts/*')
    .pipe(gulp.dest('_site/assets/fonts'));
};

const js = () => {
  console.log("Began js");
  return gulp.src(['_assets/js/*.js'])
    .pipe(debug())
    .pipe(babel({
    presets: ['es2015']
  }))
    //.pipe(concat('scripts.js')) //as of 2/10/17, status is 'failing' https://www.npmjs.com/package/gulp-concat
    .pipe(uglify())
    .pipe(gulp.dest('_site/assets/js'));
};
const reload_site = (done) => {
  console.log("Began reload");
  return (browserSync.reload() || true) && done();
};
const total_reload = () =>{
  return gulp.series( 'jekyll_build', gulp.parallel('js', 'css', 'fonts'), 'reload_site');
}
const serve = () => {
  browserSync.init({
        server: "_site"
    });
    gulp.watch('_assets/js/*.js', total_reload());
  gulp.watch('_assets/css/*.css', total_reload());
  gulp.watch(['*.html', '_layouts/*.html', '_sections/*', '**/*.html', '!_site/*']).on('change', total_reload());

};


gulp.task('css', css);
gulp.task('js', js);
gulp.task('fonts', fonts);
gulp.task('clean', clean);
gulp.task('clean_unneeded', clean_unneeded);
gulp.task('jekyll_build', jekyll_build);
gulp.task('total_reload', total_reload);
gulp.task('serve', serve);
gulp.task('reload_site', reload_site);
gulp.task('useref_task', useref_task);
gulp.task('build',  gulp.series('clean', 'jekyll_build', gulp.parallel('js', 'css', 'fonts'), 'useref_task', 'clean_unneeded'));
gulp.task('default', gulp.series('clean', 'jekyll_build', gulp.parallel('js', 'css', 'fonts'), 'useref_task', 'clean_unneeded', 'serve'));