While javascript might be the fastest and easiest way to
check for required fields, it's not a true way to verify
that a required field has been filled in. It's a great way
to offload some traffic by making sure that the form is
filled out before sending the data across the network, but
can be easily gotten around since javascript can be disabled.
In order to thoroughly check that fields are filled in,
server-side checking has to be done, in addition to any
client-side checks.