update to gulp 4.0.0

gulpfile.js

@@ -1,9 +1,8 @@
-var gulp = require('gulp'),
-    rimraf = require('rimraf'),
-    runSequence = require('run-sequence'),
-    merge = require('merge-stream');
+const gulp = require('gulp');
+const del = require('del');
+const merge = require('merge-stream');
 
-var paths = {};
+const paths = {};
 paths.dist = './_site/';
 paths.sass = './_sass/';
 paths.libDir = './lib/';
@@ -11,24 +10,15 @@ paths.npmDir = './node_modules/';
 paths.cssDir = './css/';
 paths.jsDir = './scripts/';
 
-gulp.task('build', function (cb) {
-    return runSequence(
-        'clean',
-        'lib',
-        cb);
-});
+function cleanLib() {
+    return del(paths.libDir)
+}
 
-gulp.task('clean:lib', function (cb) {
-    return rimraf(paths.libDir, cb);
-});
+function cleanDist() {
+    return del(paths.dist)
+}
 
-gulp.task('clean:dist', function (cb) {
-    return rimraf(paths.dist, cb);
-});
-
-gulp.task('clean', ['clean:lib', 'clean:dist']);
-
-gulp.task('lib', ['clean:lib'], function () {
+function lib() {
     var libs = [
         {
             src: paths.npmDir + 'bootstrap-sass/assets/javascripts/bootstrap.min.js',
@@ -59,9 +49,15 @@ gulp.task('lib', ['clean:lib'], function () {
         }
     ];
 
-    var tasks = libs.map(function (lib) {
+    var tasks = libs.map((lib) => {
         return gulp.src(lib.src).pipe(gulp.dest(lib.dest));
     });
 
     return merge(tasks);
-});
+}
+
+exports.build = gulp.series(gulp.parallel(cleanLib, cleanDist), lib);
+exports['clean:dist'] = cleanDist;
+exports['clean:lib'] = cleanLib;
+exports.clean = gulp.parallel(cleanLib, cleanDist);
+exports.lib = gulp.series(cleanLib, lib);

package.json

@@ -7,15 +7,14 @@
     "deploy": "npm run build && gh-pages --dotfiles --dist _site"
   },
   "devDependencies": {
-    "gulp": "3.9.1",
-    "rimraf": "2.6.1",
-    "run-sequence": "2.1.0",
-    "merge-stream": "1.0.1",
     "bootstrap-sass": "3.3.7",
+    "fluidbox": "2.0.5",
     "font-awesome": "4.7.0",
+    "gh-pages": "^1.2.0",
+    "gulp": "^4.0.0",
     "jquery": "2.2.4",
     "lunr": "0.7.1",
-    "fluidbox": "2.0.5",
-    "gh-pages": "^1.2.0"
+    "merge-stream": "1.0.1",
+    "del": "^3.0.0"
   }
 }