Small volunteer page fixes

[struan]

This sorts out a number of small issues with the volunteer management pages.

Fixes #157
Fixes #172
Fixes #173
Fixes #174

[zarino]

All seems sensible. Just two largely stylistic comments. Feel free to adopt or ignore!

[zarino]

$id $(selector).eq(0)` will always be truthy, even when the selector matches nothing, because it’ll still return a jQuery object, which is truthy.

You probably want either $id.length, or, even simpler, drop the $id && entirely and just rely on $id.val(), since $id.val() will return the falsey undefined if the no elements matched the selector.

[zarino]

FWIW jQuery has a built-in function to construct query strings like this – $.param(), which has the advantage of also URL-encoding the keys and values, so they’re safe to append to a URL. eg:

url = url + '?' + $.param({
  rt: $rt.val(),
  s: $section.val(),
  ms: $session.val()
});

You could even store everything in a variable at first, then conditionally add your id item (below), and then parametrize them all in one go at the end, eg:

var params = {
  rt: $rt.val(),
  s: $section.val(),
  ms: $session.val()
};

if (…) {
  params["id"] = $id.val();
}

url = url + '?' + $.param(params);

Or even (replacing the need to declare $session, $section, and $rt up front, since you never use them again anyway):

var params = {
  rt: $fs.find('.field_rt').eq(0).val(),
  s: $fs.find('.field_section').eq(0).val(),
  ms: $fs.find('.field_session').eq(0).val()
};

if (…) {
  params["id"] = $id.val();
}

url = url + '?' + $.param(params);

Just a thought!