Years ago I learned PHP because someone else's web form was broken, and I needed to fix it. Apparently this kind of perforce-introduction to PHP is pretty common (and, some say, tends to form bad habits early), so I don't feel too bad about never having learned the language formally.

The result, though, is that my web programming brain leans pretty heavily server-side.

If you're like me, then Stoyan Stefanov's introduction to JavaScript for PHP developers might prove extremely useful.

Stoyan seems like a perfect person to learn from -- he's written six books on JavaScript and PHP -- and his blogpost and presentation are both very clear. For example, here's a PHP associative array:

$fido = array(
  'name' => "Fido",
  'barks' => true
);

and here's the JavaScript object literal he compares it to:

var fido = {};
fido.name = "Fido";
fido.barks = true;

The slideshare presentation, which compares many syntax feature side-by-side, is embedded below. Click through it, or check out Stoyan's article for a more compressed version with lots of helpful comments.