What, you might ask, is a syntax error?
I did some googling, and some asking, and apparently the majority of syntax errors have to do with punctuation — such as forgetting to close a line with a semicolon, or forgetting parentheses.
I stared at the code. Stared some more. Then I finally had the bright idea to compare my code with another example of jquery that was working (I used this), and that was where I immediately saw that I was missing an entire set of closing parentheses });.
Whoops! Guess that I means I need to reread my book. Or just start practicing with some more examples.
Hurrah for super-helpful co-workers! Sometimes it’s good to have mentors who know their stuff. And to cross-check code with a working example rather than staring at it blindly, of course.