I would like to add some inline javascript that alerts the user with a message AND then returns false, preventing the form from submitting.

onsubmit=return alert('You must be logged in to register'); return false

With the code above, I get the alert but the form still submits. I would like to retain the inline JS if possible. I searched around but couldn't find an inline example that follows this pattern. I know how to achieve this by executing a function with onsubmit, but again, would like to retain inline if possible.