2 questions about checkbox into form

Fred · Oct 24, 2004

Hi,

I defined a form consisting of checkboxes like:
<form>
<input type="checkbox" name=ck id=ck onclick="check(this.form)"
<input type="checkbox" name=ck id=ck onclick="check(this.form)"
.....
<input type="checkbox" name=ck id=ck onclick="check(this.form)"
</form>

1) when this function is ran, if there is only ONE checkbox into the form, i
get in the first ALERT: "undefined" and the second gives a value of 0. When
there are 2 ore more, i get the exact length and the right number of checked
checkboxes..
My question is: why and how to solve this?
function check(form)
{
var total = 0;
var mx = form.ck.length;
alert(mx)

for (var x = 0; x < mx; x++)
{
if (eval("document.chk.ck[" + x + "].checked") == true)
{ total += 1 }
}
alert(total)

2) When one checkbox is checked, i would like to disabeld all the others,
because only one may be checked.
I tried different ways, but no succesfully (in the same function as above):
"impossible to affect to a result of function" (or something ..)

if (total==1)
{
for (var x = 0; x < mx; x++)
{
if (eval("document.chk.ck[" + x + "].checked") == false)
{eval("document.chk.ck[" + x + "].disabled") = true}
}
}

Thanks again for any hints
Fred

thorpe · Oct 24, 2004

what makes you think this has anything to do with asp?

Bob Barrows [MVP] · Oct 24, 2004

As thorpe says, this has nothing to do with ASP, and should have been posted
to a javascript or client-side scripting newsgroup, such as
..scripting.jscript, or one of the groups with "dhtml" in their names.
However, I will attempt to answer this below, so that your time will not
have been totally wasted. Please followup in the appropriate newsgroup
however. (cc'ed and Followup-to set to microsoft.public.scripting.jscript)

Fred said:
Hi,

I defined a form consisting of checkboxes like:
<form>
<input type="checkbox" name=ck id=ck onclick="check(this.form)"
<input type="checkbox" name=ck id=ck onclick="check(this.form)"
....
<input type="checkbox" name=ck id=ck onclick="check(this.form)"

You should give each checkbox a unique id, keeping the names the same:
<input type="checkbox" name=ck id=ck1 onclick="check(this.form)"
<input type="checkbox" name=ck id=ck2 onclick="check(this.form)"
.....
<input type="checkbox" name=ck id=ck4 onclick="check(this.form)"

</form>

1) when this function is ran, if there is only ONE checkbox into the
form, i get in the first ALERT: "undefined" and the second gives a
value of 0. When there are 2 ore more, i get the exact length and the
right number of checked checkboxes..
My question is: why and how to solve this?
function check(form)
{
var total = 0;
var mx = form.ck.length;
alert(mx)

for (var x = 0; x < mx; x++)
{
if (eval("document.chk.ck[" + x + "].checked") == true)

Get out of the habit of using eval. It is not necessary. A better technique
in this case would be:

var cks=document.getElementsByName("ck"),total = 0
for (var x = 0; x < cks.length; x++)
{
if (cks[x].checked == true)
{total += 1}
}

alert(total);

2) When one checkbox is checked, i would like to disabeld all the
others, because only one may be checked.
I tried different ways, but no succesfully (in the same function as
above): "impossible to affect to a result of function" (or something
..)

The best way to do this would be to use radio buttons instead of checkboxes.
The page would handle this for you. However,

if (total==1)
{
for (var x = 0; x < mx; x++)
{
if (eval("document.chk.ck[" + x + "].checked") == false)
{eval("document.chk.ck[" + x + "].disabled") = true}
}
}

Again with the eval! ugh! Try this:

<HTML>
<HEAD>
<SCRIPT type="text/javascript">
function check(obj)
{
var cks=document.getElementsByName("ck")
for (var x = 0; x < cks.length; x++)
{
if (cks[x].id != obj.id)
{
cks[x].checked=false;
cks[x].disabled=obj.checked;
}
}
}
</SCRIPT>
</HEAD>
<BODY>
<form id="frm1" method="post">
<INPUT type="checkbox" id="ck1" name="ck" value="1" onclick="check(this)">
<INPUT type="checkbox" id="ck2" name="ck" value="2" onclick="check(this)">
<INPUT type="checkbox" id="ck3" name="ck" value="3" onclick="check(this)">
<INPUT type="checkbox" id="ck4" name="ck" value="4" onclick="check(this)">
<INPUT type="submit" value="Submit" id=submit1 name=submit1>

</form>

Bob Barrows

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2 questions about checkbox into form

Fred

thorpe

Bob Barrows [MVP]

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