Hi,
> Shouldn't returning true exit directly from the function?
It does -- it returns from the function it's in. The function it's in
is the anonymous one that #each has called for that particular
checkbox, not the testRecipient function.
Four ways you can rewrite that to work. The first three keep using
#each, the fourth just opts for a simple loop. Here are two of the
#each options:
// #each, version 1. Keeps track of return flag, but doesn't short-
circuit the loop.
function testRecipient() {
var required = ["dir", "dev", "pub", "web"];
var okay = false;
required.each( function (name) {
if ( !okay && $(name).checked ) {
okay = true;
}
});
if ( !okay ) {
alert('Please select at least one recpipient for your
email.');
}
return okay;
}
// #each, version 2. Keeps track of return flag and terminates the
loop early.
function testRecipient() {
var required = ["dir", "dev", "pub", "web"];
var okay = false;
required.each( function (name) {
if ( $(name).checked ) {
okay = true;
throw $break; // <== The new bit, see notes
}
});
if ( !okay ) {
alert('Please select at least one recpipient for your
email.');
}
return okay;
}
(Side note: Unless you prefer it for clarity, which is fine, there's
no _technical_ reason for writing "if ( $(name).checked == true )",
simply "if ( $(name).checked )" is all you need. The statements are
functionally identical from the JS interpreter's standpoint.)
A note about that "throw $break" thing on v2: The $break object is a
special object defined by Prototype for exactly this situation,
wanting to break an #each loop early. #each catches exceptions and, if
the exception === $break, just returns early (otherwise it re-throws
the exception). But $break no longer appears in the documentation and
I think one of the core team said it was going to be dropped at some
stage.
Actually, there's a third #each option as well:
// #each, version 3. Uses an exception to report success
function testRecipient() {
var required = ["dir", "dev", "pub", "web"];
var okay = {};
try {
required.each( function (name) {
if ( $(name).checked ) {
throw okay;
}
});
}
catch (e) {
if (e === okay) {
return true;
}
}
alert('Please select at least one recpipient for your email.');
return false;
}
My problem with v2 and v3 is that they throw an exception in the
*normal* case (the user has ticked one of the required boxes). That's
not what exceptions are for, they're for _exceptional_ conditions. I
don't like v1 because it doesn't short-circuit, but it's not like it's
a long loop so that doesn't matter.
I'd probably go with a simple loop:
// A simple loop
function testRecipient() {
var required = ["dir", "dev", "pub", "web"];
var index;
for (index = 0; index < required.length; ++index) {
if ( $(required[index]).checked ) {
return true;
}
}
alert('Please select at least one recpipient for your email.');
return false;
}
...but I come from a procedural and class-based OOP background, not a
functional background. (Does that make me dysfunctional?)
Side note 2: I just noticed a typo in your error message when reading
this message back, one I faithfully reproduced in all of the above,
having read right past it. :-) "recpipient" has an extra "p" in it
(should be "recipient").
HTH,
--
T.J. Crowder
Independent Software Consultant
tj / crowder software / com
www.crowdersoftware.com
On Apr 13, 7:53 pm, sporkit <[email protected]> wrote:
> I'm trying to validate that at least one checkbox of 4 has been
> selected. The code seems simple enough to me.
>
> function testRecipient() {
> var required = ["dir", "dev", "pub", "web"];
> required.each( function (name) {
> if ( $(name).checked == true )
> return true;
> });
>
> alert('Please select at least one recpipient for your email.');
> return false;
>
> }
>
> Shouldn't returning true exit directly from the function? Even if I
> reach the return true statement, the function keeps looping until it
> reaches the alert and returns false. I could probably throw $break,
> but I feel as if I'm missing something really important here...
>
> Thanks!!!
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