Listing 1: first component, CommentBox.

.eslintrc.js

@@ -9,6 +9,7 @@ module.exports = {
   "globals": {
     "jQuery": true,
     "React": true,
+    "ReactDOM": true
   },
 
   "plugins": ["react"],

public/scripts/tutorial.js

@@ -1,7 +1,5 @@
 let CommentBox = React.createClass({
   render: function () {
-    "use strict";
-
     return (
       <div className="commentBox">
         Hello, world: I am a CommentBox.
@@ -9,3 +7,8 @@ let CommentBox = React.createClass({
     );
   }
 });
+
+ReactDOM.render(
+  <CommentBox />,
+  document.getElementById("content")
+);