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Javascript Error : Is Null or Not an Object

Answer 1

+1 A:

I do not think it is in the best interest of accessibility to dynamically alter a user's focus prior to alerting the user of such a change. What you can do that is accessible is redirect a user to a fragment URI pointing to the id attribute of the document object in question. That way you are not having to use any JavaScript.

So, for instance, if a user requests a page at this URI:
http://example.com/page.html

You can redirect the user with your ASP code and a HTTP 302 code to this page:
http://example.com/page.html#myInputIDValue

That would presume the input field in question had the following attribute:
id="myInputIDValue"

2010-02-22 06:25:26

hi jjj < body onload="document.getElementById('UserInputTextBox').focus();" > is not working thanks for ur help

2010-02-22 06:39:37

thanks for all who have answered it got worked when i called the function as follows<asp:UpdatePanel ID="UpdatePanel1" runat="server" UpdateMode="Conditional"> <ContentTemplate><input id="UserInputTextBox" type="text" size="75" maxlength="300" runat="server" /><script type="text/javascript" >window.onload=function(){document.getElementById('UserInputTextBox').focus();}</script></ContentTemplate></asp:UpdatePanel>

2010-02-22 07:16:51

Answer 2

+1 A:

You've got to wait for the DOM to be ready before trying to access elements in the dom; The onload event listener can wait for the entire document to be loaded including images and css... Which might be undesirable.

<head>
    <script type="text/javascript" charset="utf-8">
        // wait for the DOCUMENT to become ready.
        window.onload=function(){
          walkmydog()
        }
    </script>
</head>

Here's a detailed explanation for overcoming this sort of problem: http://www.javascriptkit.com/dhtmltutors/domready.shtml

A lot of people use javascript frameworks, like jQuery, MooTools, YUI, to overcome the browse incompatibility problems.

peterp 2010-02-22 06:38:57

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Javascript Error : Is Null or Not an Object

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