Add JS watch convenience script

Add a convenience script to run the default gulp command, which rebuilds the
frontend on file change. Also add linting to the default and watch commands.

README.md

@@ -16,7 +16,7 @@ Development Installation
 3. Copy `deployment/ansible/group_vars/development_template` to `deployment/ansible/group_vars/development`
 4. Run `vagrant up`
 5. See the app at http://localhost:8024! See OpenTripPlanner at http://localhost:9090.
-6. Running `npm run gulp` from `/opt/app/src` will rebuild the front-end app on file change (the browser must be reloaded manually to pick up the change). Alternatively, `npm run gulp-development` can be run manually whenever changes are made to the static files.
+6. Running `./scripts/serve-js-dev.sh` on the host will rebuild the front-end app on file change (the browser must be reloaded manually to pick up the change). Alternatively, `cd /opt/app/src && npm run gulp-development` can be run manually in the VM to pick up changes to the static files.
 
 Note that if there is an existing build Graph.obj in `otp_data`, vagrant provisioning in development mode will not attempt to rebuild the graph, but will use the one already present.
 

scripts/serve-js-dev.sh

@@ -0,0 +1,7 @@
+#!/bin/bash
+
+set -x
+
+# Run JS and styles watcher to rebuild frontend on file change
+# (Page reload still required)
+vagrant ssh app -c "cd /opt/app/src && npm run gulp"

src/gulpfile.js

@@ -328,7 +328,7 @@ gulp.task('watch', function () {
         'app/scripts/**/*.js',
         'app/styles/**/*.css',
         'app/styles/**/*.scss'
-    ], { usePolling: true }, gulp.parallel('development'));
+    ], { usePolling: true }, gulp.parallel('jshint', 'development'));
 });
 
-gulp.task('default', gulp.series('development', 'watch'));
+gulp.task('default', gulp.series('jshint', 'development', 'watch'));