Improve indentation and highlighting on some JS code snippets

[missmatsuko]

• Fixes some code not lining up
• Fixes some JS snippets not having JS highlighting
• Fixes non-JS code with JS highlighting

[svinkle]

@missmatsuko I think I made some changes recently to cause the conflicts here. Can you rebase or fix these up first, and I'll take another look.

[missmatsuko]

Rebased, should be good now!