When button is disabled, it’s not-clickable in all browsers. However in Firefox and Chrome, the button looks enabled, though the user cannot click it.

Reason:

From W3Scholl, "Enabled" Property isn't standard property of XHTML 4.

Solution:

You can modify the way they look with CSS

button[disabled] { 
 color:Grey;
/* Add other  styles here for disable button */ 
} 

I came across a bug with Google chrome ver 1.0.154.43 while answering a problem in asp.net forums.

Problem:

Chrome browser ignores "onblur" event function for input box while it has Required field validator attached to it . Check this code..

  <input id="txt1" runat="server" type="text" maxlength="16" style="width: 127px" onblur= "formatSSN();"/>

  <asp:RequiredFieldValidator ID="Rfssn" runat="server" ControlToValidate="txt1" Display="None" ErrorMessage="SSN" 

     SetFocusOnError="True" EnableViewState="False">

  </asp:RequiredFieldValidator>

  <script language="javascript" type="text/javascript">

   function formatSSN() 

  {

    var ssn = document.getElementById("txt1").value;

    if(ssn.length == 9) 

        {

            document.getElementById("txt1").value= ssn.substring(0, 3) +"-" + ssn.substring(3, 5) + "-" + ssn.substring(5, 9); 

            return false;

        }

  }

  </script> 

The code works fine in IE6/7 & FireFox3, but not in Google chrome .

Solution:

I think the problem is with required field validator's SetFocusOnError property. Setting SetFocusOnError="false" for Rfv will fix it in chrome.

Here is an example to validate Fileupload control. This validation will check user to upload files of particular type/extension.

Client side validation:

<asp:FileUpload ID="UploadFile" runat="server" />
<asp:Button Text="Save" ID="btnSave" runat="server" OnClientClick="javascript:return ValidateUpload();" />     
 <script type="text/javascript" language="javascript">
    function ValidateUpload()
            {           
                var Upload_file = document.getElementById('<%= UploadFile.ClientID %>');                
                var myfile = Upload_file.value;               
                if(myfile.indexOf("doc")>0)
                {
                 alert('Valid Format');
                }
                else
                {
                 alert('Invalid Format');
                }            
            }
 </script>
Validating with RegularExpression validator:

<asp:FileUpload ID="UploadFile" runat="server" />
<asp:RegularExpressionValidator ID="RegularExpressionValidator1" runat="server" ErrorMessage="Only Doc files are allowed" 
ControlToValidate="UploadFile" ValidationExpression="^(([a-zA-Z]:)|(\\{2}\w+)\$?)(\\(\w[\w].*))+(.doc|.DOC)$">
</asp:RegularExpressionValidator>

In this example, I checked  ".doc" file type but you can use this example for any file type. Just replace ".doc" with file type you would  like to check( "Xml", "wmv"...).

Microsoft is going to make jQuery part of the official dev platform. JQuery will come with Visual Studio in the long term, and in the short term it'll ship with ASP.Net MVC. It is truly good news for ASP.Net developers

What is jQuery?

jQuery is a lightweight open source JavaScript library.

From jQuery website..

jQuery is a fast and concise JavaScript Library that simplifies HTML document traversing, event handling, animating, and Ajax interactions for rapid web development.

Blogs posts by Scott Guthrie and Scott Hanselman on this topic.

I see questions asked frequently about FireFox rendering problems in Asp.Net forums.

What is "rendering engine"?

A rendering engine, also known as a layout engine, is the code that tells the browser how to display web content and available style information in the browser window

Here are some options to solve those:

1. Always check  rendered web pages for XHTML compatibility using the W3C tests at   http://validator.w3.org . Most issues will fixed by fixing all non standards compliant HTML.
2. Set clientTarget="UpLevel" in Page Directive. This will override automatic detection of browser capabilities and specifies how a page renders for particular browser clients.
3. Here is link to a guide to make your page as accessible as possible.   http://www.anybrowser.org/campaign/abdesign.html

Here is a way of detecting search engine (Google, live…) crawlers,spiders etc..

[code:c#]
            System.Web.HttpBrowserCapabilities clientBrowserCaps = Request.Browser;
            if (((System.Web.Configuration.HttpCapabilitiesBase)clientBrowserCaps).Crawler)
            {
                Response.Write ( "Browser is a search engine.");
            }
            else
            {
               Response.Write ("Browser is not a search engine.");
            } 

//Here is another approach..

            if (Request.ServerVariables["HTTP_USER_AGENT"].Contains("Googlebot"))
            {
                //log Google bot visit
            }
            else if (Request.ServerVariables["HTTP_USER_AGENT"].Contains("msnbot"))
            {
                //log MSN bot visit
            }
            else if (Request.ServerVariables["HTTP_USER_AGENT"].Contains("Yahoo"))
            {
                //log yahoo bot visit
            }
            else
            {
                //similarly you can check for other search engines
            }

[/code]

Here is a small code to remove spaces from textbox's text in onblur event.

<asp:TextBox ID="TextBox2" runat="server" onblur="javascript:value=value.replace(/\s/g,'');"></asp:TextBox>

To remove HTML tags..

<asp:textbox id="TextBox2" runat="server" onblur="this.value = this.value.replace(/<\/?[^>]+>/gi, '');">
</asp:textbox>

Please let me know, if you have any issues.

Here is a way of changing back ground color for Textbox on validation failure. The key here is using Page_ClientValidate function in javascript.

<asp:TextBox ID="TextBox1" runat="server"></asp:TextBox>
<asp:RequiredFieldValidator ID="RequiredFieldValidator1" runat="server" ErrorMessage="Please enter a value"
    ControlToValidate="TextBox1"></asp:RequiredFieldValidator>
<asp:Button ID="Button1" runat="server" Text="Button" OnClientClick="btnClick();"
    OnClick="Button1_Click1" />

<script type="text/javascript"> 

    function btnClick() 
    { 
        if (!Page_ClientValidate()) 
        { 
            document.getElementById("TextBox1").style.backgroundColor="red"; 
        } 
    } 

    function ClearBackGround() 
    { 
        document.getElementById("TextBox1").style.backgroundColor=""; 
    } 

</script>

In Code behind

TextBox1.Attributes.Add("onkeypress", "ClearBackGround()");

The browser back button cannot be disabled as the browser security will not allow this. If you want user to stay on the same page, even if user presses back button, try this java script..

<script language="JavaScript">

javascript:window.history.forward(1);

</script>

What if the JavaScript is disabled by the client, then this code doesn't work. And also it works great in IE, but not in other browsers. So I do not highly recommend using this.

Here is another solution for back button problem..

Add this code to Page_load

Response.Cache.SetCacheability(HttpCacheability.NoCache);

Response.Cache.SetExpires(DateTime.Now); 

The above code will disable page cache. Since the page is not being cached on the browser, the page will be reloaded when the user hits the back button.

HTTP(web page) is stateless, so we cannot know whether the Session has really expired without sending a page request back to the server. If you want to redirect the page immediately(with out any user action) after session expires consider this approach.

Response.AppendHeader("Refresh",Convert.ToString((Session.Timeout * 60)+ 10)+";URL=Login.aspx");

Add this line of code to page_Load.