Use Gulp 4.x

Gulpfile.js

@@ -10,21 +10,20 @@ const sourcemaps  = require('gulp-sourcemaps');
 const babel       = require('gulp-babel');
 
 
-// gulp -> gulp watch
-gulp.task('default', ['watch']);
-
-
-// gulp lint -> errors if code dirty
-gulp.task('lint', function () {
+function lint() {
   return gulp.src([ 'src/**/*.js', 'test/*.js' ])
     .pipe(eslint())
     .pipe(eslint.formatEach())
     .pipe(eslint.failOnError());
-});
+}
 
 
-// gulp build -> compile coffee script
-gulp.task('build', ['clean'], function() {
+function clean() {
+  return del('lib/**');
+}
+
+
+function build() {
   return gulp.src('src/**/*.js')
     .pipe(sourcemaps.init())
     .pipe(babel())
@@ -34,23 +33,31 @@ gulp.task('build', ['clean'], function() {
       message: 'Zombie: built!',
       onLast:  true
     }));
-});
+}
 
 
-// gulp clean -> clean generated files
-gulp.task('clean', function() {
-  return del('lib/**');
-});
+function watch() {
+  return gulp.watch('src/*.js', gulp.series(clean, build));
+}
 
 
-// gulp watch -> watch for changes and compile
-gulp.task('watch', ['build'], function() {
-  return gulp.watch('src/*.js', ['clean', 'build']);
-});
+// Generate a change log summary for this release
+// git tag uses the generated .changes file
+function changes() {
+  const version   = require('./package.json').version;
+  const changelog = File.readFileSync('CHANGELOG.md', 'utf-8');
+  const match     = changelog.match(/^## Version (.*) .*\n([\S\s]+?)\n##/m);
 
+  assert(match, 'CHANGELOG.md missing entry: ## Version ' + version);
+  assert.equal(match[1], version, 'CHANGELOG.md missing entry for version ' + version);
 
-// gulp tag -> Tag this release
-gulp.task('tag', ['changes'], function() {
+  const changes   = match[2].trim();
+  assert(changes, 'CHANGELOG.md empty entry for version ' + version);
+  File.writeFileSync('.changes', changes);
+}
+
+
+function tag() {
   const version = require('./package.json').version;
   const tag     = 'v' + version;
 
@@ -61,20 +68,19 @@ gulp.task('tag', ['changes'], function() {
     .pipe( exec('git tag ' + tag + ' --file .changes') )
     .pipe( exec('git push origin ' + tag) )
     .pipe( exec('git push origin master') );
-});
-
-// Generate a change log summary for this release
-// git tag uses the generated .changes file
-gulp.task('changes', function() {
-  const version   = require('./package.json').version;
-  const changelog = File.readFileSync('CHANGELOG.md', 'utf-8');
-  const match     = changelog.match(/^## Version (.*) .*\n([\S\s]+?)\n##/m);
+}
 
-  assert(match, 'CHANGELOG.md missing entry: ## Version ' + version);
-  assert.equal(match[1], version, 'CHANGELOG.md missing entry for version ' + version);
 
-  const changes   = match[2].trim();
-  assert(changes, 'CHANGELOG.md empty entry for version ' + version);
-  File.writeFileSync('.changes', changes);
-});
+// gulp build -> compile coffee script
+exports.build = gulp.series(clean, build, lint);
+// gulp clean -> clean generated files
+exports.clean = clean;
+// gulp lint -> errors if code dirty
+exports.lint = lint;
+// gulp watch -> watch for changes and compile
+exports.watch = gulp.series(build, watch);
+// gulp tag -> Tag this release
+exports.tag = gulp.series(changes, tag);
+// gulp -> gulp watch
+exports.default = exports.watch;