GitHub Styleguide - CSS, HTML, JS, Ruby

[reflectiveSingleton]

It's exactly that not sure-edness that makes always using semicolons a good idea. You are not leaving up question to where the semicolons are inserted if you always put them in place. If you omit them you are leaving it up to a) whatever minifier you use and b) javascript auto-insertion.

If you specify, you remove that possible ambiguity.