Shows how to disable a button on submit in ASP.NET while maintaining validation checks and form submission

SingleClick

public static class HtmlHelper
{
    private const string DISABLED_BUTTON_CSS_CLASS = "disabled_button";

    public static void SingleClick(Page page, Button btn)
    {
        string scriptKey = String.Format("click_once_button_{0}", btn.ValidationGroup);

        if (!page.ClientScript.IsClientScriptBlockRegistered(scriptKey))
        {
            StringBuilder sb = new StringBuilder();
            sb.Append("function disableButtonOnClick(btn) ");
            sb.Append("{");
            sb.Append(" if(typeof(Page_ClientValidate) == 'function') ");
            sb.Append("{");
            sb.AppendFormat(" if(Page_ClientValidate('{0}') == false)", btn.ValidationGroup);
            sb.Append(" {");
            sb.Append(" return false;");
            sb.Append(" }");
            sb.Append(" btn.disabled = true;");
            sb.Append(" btn.value = 'Working ...';");
            sb.AppendFormat(" btn.setAttribute('className', '{0}');", DISABLED_BUTTON_CSS_CLASS);
            sb.AppendFormat(" btn.setAttribute('class', '{0}');", DISABLED_BUTTON_CSS_CLASS);
            sb.Append(" }");
            sb.Append(" }");

            page.ClientScript.RegisterClientScriptBlock(typeof(HtmlHelper), scriptKey, sb.ToString(), true);

            btn.UseSubmitBehavior = false;

            PostBackOptions options = new PostBackOptions(btn);

            btn.OnClientClick = "disableButtonOnClick(this);" + page.ClientScript.GetPostBackEventReference(options) + ";return;";
        }
    }
}