Update: In the past few years the landscape has changed drastically. You can now reliably use querySelector and querySelectorAll, see Wojtek’s answer for how to do this.
There’s no need for a jQuery dependency now. If you’re using jQuery, great…if you’re not, you need not rely it on just for selecting elements by attributes anymore.
There’s not a very short way to do this in vanilla javascript, but there are some solutions available.
You do something like this, looping through elements and checking the attribute
If a library like jQuery is an option, you can do it a bit easier, like this:
$("[myAttribute=value]")
If the value isn’t a valid CSS identifier (it has spaces or punctuation in it, etc.), you need quotes around the value (they can be single or double):
$("[myAttribute='my value']")
You can also do start-with, ends-with, contains, etc…there are several options for the attribute selector.