Minor issue, but I noticed that the code sample used in lesson 1.2.21 wraps a post title and author in opening tags instead of opening and closing tag (e.g. '<h2>' + title + '<h2>' instead of '<h2>' + title + '</h2>').
The JS Bin code example also has a header comment for that code block that’s for a different lesson (1.2.20.1 instead of 1.2.21.3).