Webform checkbox value in javascript

Question

Hi,

I have a checkbox list control on my asp.net web form that I am dynamically populating from an arraylist. In javascript I want to be able to iterate through the values in the list and if a particular value has been selected to display other controls on the page.

My issue is that all the values in the checkbox list are showing up as 'on' instead of the actual value set. How do I get the actual values for each checkbox?

Thanks.

Javascript:

checkBoxs=document.getElementById(CheckboxList);
    var options=checkBoxs.getElementsByTagName('input');       

    for(var i=0;i<options.length;i++)
    {            
        if(options[i].value=="Other")
        {
            if(options[i].checked)
            {
                var  otherPub=document.getElementById('<%=alsOtherPublicity.ClientID%>');
                otherPub.style.display='block';

            }                
        } 

    }

Edit: The line that I'm having problems with is if(options[i].value=="Other") as the values showing up in firebug are given as 'on' rather than the values that I set.

Edit 2: The html that is produces looks like:

<span id="ctl00_ContentPlaceHolderMetadata_Allocation1_alfPublicity" class="ucFieldCBL" onChange="alValidate();" onClick="alPublicity('ctl00_ContentPlaceHolderMetadata_Allocation1_alfPublicity');">
  <input id="ctl00_ContentPlaceHolderMetadata_Allocation1_alfPublicity_0" type="checkbox" name="ctl00$ContentPlaceHolderMetadata$Allocation1$alfPublicity$0"/>
  <label for="ctl00_ContentPlaceHolderMetadata_Allocation1_alfPublicity_0">Text1</label>
  <input id="ctl00_ContentPlaceHolderMetadata_Allocation1_alfPublicity_1" type="checkbox" name="ctl00$ContentPlaceHolderMetadata$Allocation1$alfPublicity$1"/>
  <label for="ctl00_ContentPlaceHolderMetadata_Allocation1_alfPublicity_1">Text2</label>
  <input id="ctl00_ContentPlaceHolderMetadata_Allocation1_alfPublicity_2" type="checkbox" name="ctl00$ContentPlaceHolderMetadata$Allocation1$alfPublicity$2"/>
  <label for="ctl00_ContentPlaceHolderMetadata_Allocation1_alfPublicity_2">Text3</label>
  <input id="ctl00_ContentPlaceHolderMetadata_Allocation1_alfPublicity_3" type="checkbox" name="ctl00$ContentPlaceHolderMetadata$Allocation1$alfPublicity$3"/>
  <label for="ctl00_ContentPlaceHolderMetadata_Allocation1_alfPublicity_3">Text4</label>
  <input id="ctl00_ContentPlaceHolderMetadata_Allocation1_alfPublicity_4" type="checkbox" name="ctl00$ContentPlaceHolderMetadata$Allocation1$alfPublicity$4"/>
  <label for="ctl00_ContentPlaceHolderMetadata_Allocation1_alfPublicity_4">Text5</label>
</span>

It looks as if the issue stems from the lack of a value attribute available on the asp.net checkbox control as described by Dave Parslow. I'm currently trying a workaround by calling a function server side to return the text of the checkbox and using that instead.

Answer 1

options[i].checked will return true or false. options[i].value will give you the value attribute of the checkbox tag.

Answer 2

I think your problem is not with the javascript but with the code that is populating the checkboxes. Are you binding the ArrayList as the CheckBoxList data source or iterating through the ArrayList and adding new ListItems to the CheckBoxList. If the former, consider switching to the latter and make sure that you use the ListItem constructor that takes both text and value parameters. If you look at the HTML source I suspect that you will see that the generated code has the value parameter set to on for all of your checkboxes which means that the values weren't actually bound in the codebehind.

Answer 3

Not 100% applicable here, but be aware that if you give a checkbox a cssclass, it gets a span wrapped around it, and the class is placed on that. This causes all sorts of cross browser problems when youre navigating the dom, or disabling checkboxes

Answer 4

I realised after much playing about with prerender events that I didn't actually need to know the exact value of the checkbox as the arraylist values would be in the same order as the checkboxes. I searched through the arraylist to get the position of the value that I needed and then used that position on the list of checkboxes.

It sounds a bit fiddly and I don't know if it would work for everyone but I thought I would put it up here anyway incase it helps someone else someday.

Thanks for all your help.