Use JQuery syntax and lint file

Note we also use .trigger("change") to trigger event listeners
for the checkbox, otherwise they won't be fired.

app/views/annotations/edit.js.erb

@@ -67,9 +67,9 @@ function constructWarningMessage() {
 
 var categoryRadios = document.getElementById('category-radios');
 
-categoryRadios.addEventListener('click', function(evt) {
+categoryRadios.addEventListener('click', function (evt) {
   if (evt.target && event.target.matches("input[type='radio']")) {
-    switch(evt.target.value) {
+    switch (evt.target.value) {
       case Category.NOTE.name:
         note();
         break;
@@ -100,7 +100,7 @@ function content() {
   visibleForTeacher(true);
   postComment(false);
   var contentCategoryRadios = document.getElementById('content-category-radios');
-  contentCategoryRadios.addEventListener('click', function(evt) {
+  contentCategoryRadios.addEventListener('click', function (evt) {
     if (evt.target && event.target.matches("input[type='radio']")) {
       submitButton.disabled = false;
       switch (evt.target.value) {
@@ -180,13 +180,13 @@ function updatePreview() {
 /*
  * Auxiliary methods
  */
-function visibleForTeacher(boolean) {
-  $('#annotation_visible_for_teacher').prop("checked", boolean);
+function visibleForTeacher(isVisible) {
+  $('#annotation_visible_for_teacher').prop("checked", isVisible).trigger("change");
 }
 
-function postComment(boolean) {
-  boolean = posted ? true : boolean;
-  $('#annotation_post_as_comment').prop("checked", boolean);
+function postComment(isVisible) {
+  isVisible = posted ? true : isVisible;
+  $('#annotation_post_as_comment').prop("checked", isVisible).trigger("change");
 }
 
 function previewCSS(show, modalWidth, contentWidth, previewWidth) {
@@ -209,8 +209,8 @@ function previewCSS(show, modalWidth, contentWidth, previewWidth) {
 /* If this script is rendered by the edit method of the annotation controller:
    Select correct subcategory (this is not automatically done by the rails form
    as the content is dynamically rendered). */
-var contentRadio = document.getElementById('annotation_category_content');
-if (contentRadio.checked) {
+var contentRadio = $('#annotation_category_content');
+if (contentRadio.is(':checked')) {
   content();
   submitButton.disabled = false;
   var subcategory = document.getElementById('annotation_subcategory').textContent.replace(/[^a-z]/g, '');
@@ -229,15 +229,15 @@ if (contentRadio.checked) {
 
 // render preview
 var annotationComment = document.getElementById('annotation_comment');
-annotationComment.addEventListener('input', function() {
+annotationComment.addEventListener('input', function () {
   updatePreview();
 });
 
 previewCSS(false, 100, 100, 0);
 
 // preview toggle listener
 var previewToggle = document.getElementById('preview-toggle');
-previewToggle.addEventListener('change', function() {
+previewToggle.addEventListener('change', function () {
   if ($('#preview-toggle-check').is(":checked")) {
     previewCSS(true, 150, 65, 35);
   } else {