Disable button on form submission

I have a button that I would like to disable when the form submits to prevent the user submitting multiple times.

I have tried naively disabling the button with javascript onclick but then if a client side validation that fails the button remains disabled.

How do I disable the button when the form successfully submits not just when the user clicks?

This is an ASP.NET form so I would like to hook in nicely with the asp.net ajax page lifecycle if possible.

I'm not a huge fan of writing all that javascript in the code-behind. Here is what my final solution looks like.

Button:

<asp:Button ID="btnSubmit" runat="server" Text="Submit" OnClick="btnSubmit_Click" OnClientClick="doSubmit(this)" />

Javascript:

<script type="text/javascript"><!--
function doSubmit(btnSubmit) {
    if (typeof(Page_ClientValidate) == 'function' && Page_ClientValidate() == false) { 
        return false;
    }    
    btnSubmit.disabled = 'disabled';
    btnSubmit.value = 'Processing. This may take several minutes...';
    <%= ClientScript.GetPostBackEventReference(btnSubmit, string.Empty) %>;    
}
//-->
</script>

Give this a whirl:

using System;
using System.Collections.Generic;
using System.Linq;
using System.Web;
using System.Web.UI;
using System.Web.UI.WebControls;
using System.Threading;

public partial class _Default : System.Web.UI.Page 
{
    protected void Page_Load(object sender, EventArgs e)
    {

         // Identify button as a "disabled-when-clicked" button...
         WebHelpers.DisableButtonOnClick( buttonTest, "showPleaseWait" ); 
    }

    protected void buttonTest_Click( object sender, EventArgs e )
    {
        // Emulate a server-side process to demo the disabled button during
        // postback.
        Thread.Sleep( 5000 );
    }
}



using System;
using System.Web;
using System.Web.UI.WebControls;
using System.Text;

public class WebHelpers
{
    //
    // Disable button with no secondary JavaScript function call.
    //
    public static void DisableButtonOnClick( Button ButtonControl )
    {
        DisableButtonOnClick( ButtonControl, string.Empty );    
    }

    //
    // Disable button with a JavaScript function call.
    //
    public static void DisableButtonOnClick( Button ButtonControl, string ClientFunction )
    {   
        StringBuilder sb = new StringBuilder( 128 );

        // If the page has ASP.NET validators on it, this code ensures the
        // page validates before continuing.
        sb.Append( "if ( typeof( Page_ClientValidate ) == 'function' ) { " );
        sb.Append( "if ( ! Page_ClientValidate() ) { return false; } } " );

        // Disable this button.
        sb.Append( "this.disabled = true;" ); 

        // If a secondary JavaScript function has been provided, and if it can be found,
        // call it. Note the name of the JavaScript function to call should be passed without
        // parens.
        if ( ! String.IsNullOrEmpty( ClientFunction ) ) 
        {
            sb.AppendFormat( "if ( typeof( {0} ) == 'function' ) {{ {0}() }};", ClientFunction );  
        }

        // GetPostBackEventReference() obtains a reference to a client-side script function 
        // that causes the server to post back to the page (ie this causes the server-side part 
        // of the "click" to be performed).
        sb.Append( ButtonControl.Page.ClientScript.GetPostBackEventReference( ButtonControl ) + ";" );

        // Add the JavaScript created a code to be executed when the button is clicked.
        ButtonControl.Attributes.Add( "onclick", sb.ToString() );
    }
}

The following function is useful without needing the disabling part which tends to be unreliable. Just use "return check_submit();" as part of the onclick handler of the submit buttons.

There should also be a hidden field to hold the form_submitted initial value of 0;

<input type="hidden" name="form_submitted" value="0">

function check_submit (){
            if (document.Form1.form_submitted.value == 1){
                alert("Don't submit twice. Please wait.");
                return false;
            }
            else{
                document.Form1.form_submitted.value = 1;
                return true;
            }
            return false;
    }