document.getElementById("chkBox") is null

Question

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Hi.. i got problems with document.getElementById("chkBox") is null.
here is my javascript :

C#

function Check()
        {
              if(document.getElementById("chkBox").checked=true)
              {
                  document.getElementById("NA").style.display = "none";

              }

else{}}

html code:

XML

<form name="check">
                        <input type="checkbox" name="chkBox" onclick="Check()" runat="server"/>
                       
                     </form>

Posted 27-Sep-10 17:20pm

MissNano

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4 solutions

Solution 2

hello,

I also noticed that you are using document.getElementById but there is no id attribute.

<input type="checkbox" id="chkBox" name="chkBox" onclick="Check()" runat="server"/>

Posted 27-Sep-10 18:07pm

Bryian Tan

Comments

MissNano 28-Sep-10 1:15am

nope still return the same error

Solution 4

Javascript:

XML

<script>
function Check()
{
if(document.getElementById("chkBox").checked)
{
  document.getElementById("NA").style.display = "none";
}
else
{
  document.getElementById("NA").style.display = "block";
}
}
</script>

HTML

XML

<form name="check">
<input type="checkbox" name="chkBox" onclick="Check()" runat="server"/>Click
</form>
<div id="NA">This is test</div>

This works on my browser

Posted 27-Sep-10 18:54pm

Om Prakash Pant

Comments

MissNano 28-Sep-10 1:18am

doesnt work in my browser.. im using Firefox..

Solution 1

if(document.getElementById("chkBox").checked=true)

should be

if(document.getElementById("chkBox").checked==true)

Posted 27-Sep-10 17:54pm

Om Prakash Pant

Comments

MissNano 27-Sep-10 23:57pm

nope.. still return the same error.

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Sandeep Mewara · Accepted Answer · 2010-09-27T18:18:00

Solution 3

XML

<input type="checkbox" name="chkBox" onclick="Check()" runat="server"/>

1. Your checkbox is a server control
2. You have not given any ID to your control and trying to access via getElementbyID

Based on your code, make the following change and it should work:
1. Remove runat="server"
2. Put ID="chkBox"

Posted 27-Sep-10 18:18pm

Sandeep Mewara

Comments

MissNano 28-Sep-10 1:22am

Reason for my vote of 5
Automatic vote of 5 for accepting answer.

MissNano 28-Sep-10 1:26am

its working thanks you Sandeep~ :)

Sandeep Mewara 28-Sep-10 1:45am

Good to know!