Can’t find variable __doPostBack

Question

Im programming my first asp.net website
To work on iPhone safari.

My code in default.aspx body :

<div id="pnlLogin" class="panel" selected="true" >
    <h2>Login Details</h2>
    <form ID="fLogin" runat="server" class="panel" selected="true" > 
        <fieldset>
            <div class="row">
                <label>Name</label>
                <asp:TextBox id="txtUserName" runat="server" placeholder="Your username" />
            </div>
            <div class="row">
                <label>Password</label>
                <asp:TextBox id="txtPassword" textmode="Password" runat="server" placeholder="Your password" />
            </div>
        </fieldset>
        <asp:LinkButton id="btnLogin" class="whiteButton" text="Log me in!" runat="server" onclick="Login_Clicked" />
    </form> 
</div>

In backend .cs file of default.aspx :

    protected void Login_Clicked(object sender, EventArgs e)
    {
        var username = txtUserName.Text;
        var password = txtPassword.Text;

        if (username == "masi" && password == "pass")
        {
            Response.Redirect("ControlPanel.aspx");
        }
    }

Full Page Source from DESKTOP Safari :

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Strict//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-strict.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en">
    <head><title>
    Cover Plus
</title><meta id="viewport" name="viewport" content="width=device-width, user-scalable=0, initial-scale=1.0" /><link href="iui/iui.css" rel="stylesheet" type="text/css" /><link title="default" href="iui/t/default/default-theme.css" rel="stylesheet" type="text/css" />
        <script type="application/x-javascript" src="iui/iui.js"></script>


        <link rel="apple-touch-icon" href="img/touch-icon-iphone.png" /><link rel="apple-touch-icon" sizes="72x72" href="img/touch-icon-ipad.png" /><link rel="apple-touch-icon" sizes="114x114" href="img/touch-icon-iphone4.png" /><link rel="apple-touch-startup-image" href="img/startup.png" />
    <script type="text/javascript">
        function login()
        {
            var isVerified = Verify();
            if (isVerified) {
                ident.setAttribute("placeholder", "valid");
            }
        }
    </script>
</head>
    <body>


<div class="toolbar">
    <h1 id="pageTitle">Login</h1>
</div>

<div id="pnlLogin" class="panel" selected="true" >
    <h2>Login Details</h2>
    <form method="post" action="Default.aspx" id="fLogin" class="panel" selected="true">
<div class="aspNetHidden">
<input type="hidden" name="__EVENTTARGET" id="__EVENTTARGET" value="" />
<input type="hidden" name="__EVENTARGUMENT" id="__EVENTARGUMENT" value="" />
<input type="hidden" name="__VIEWSTATE" id="__VIEWSTATE" value="/wEPDwUKLTY2NzcyMzEwM2Rk+CbfIXzzsip63MXaBjBxcQhbraDzpmAHkc6FH4cZIiE=" />
</div>

<script type="text/javascript">
//<![CDATA[
var theForm = document.forms['fLogin'];
if (!theForm) {
    theForm = document.fLogin;
}
function __doPostBack(eventTarget, eventArgument) {
    if (!theForm.onsubmit || (theForm.onsubmit() != false)) {
        theForm.__EVENTTARGET.value = eventTarget;
        theForm.__EVENTARGUMENT.value = eventArgument;
        theForm.submit();
    }
}
//]]>
</script>


<div class="aspNetHidden">

    <input type="hidden" name="__EVENTVALIDATION" id="__EVENTVALIDATION" value="/wEWBALC/9DxDQKMrfuqAgKOsPfSCQKRnIq9D4GV4RtvQeooslP0bkLhJVOPoPu6Gt6b0rGrW9P8fPbK" />
</div> 
        <fieldset>
            <div class="row">
                <label>Name</label>
                <input name="ctl00$MainContent$txtUserName" type="text" id="MainContent_txtUserName" placeholder="Your username" />
            </div>
            <div class="row">
                <label>Password</label>
                <input name="ctl00$MainContent$txtPassword" type="password" id="MainContent_txtPassword" placeholder="Your password" />
            </div>
        </fieldset>
        <a id="MainContent_btnLogin" class="whiteButton" href="javascript:__doPostBack(&#39;ctl00$MainContent$btnLogin&#39;,&#39;&#39;)">Log me in!</a>
    </form> 
</div>

</body>
</html>

Problem :

It works fine on desktop safari/chrome, I type masi/pass and press the button and goes to new page, but on iPhone it gives me a javascript error in the console and does nothing.

it says : Javascript: Error undefined ReferenceError: Can't find variable: __doPostBack

I am completely clueless as to what to do.

Update - Solution:

I randomly deleted the little bit of javascript I had in the header (that did next to nothing) and now its working fine.

how many forms do you have? ASP .Net WebForms works with only one form..Also make sure you do not have nested forms — Adrian Iftode, Mar 23 '12 at 11:34
to the best of my knowledge I have one form per aspx page, so on the default.aspx is only 1 form. — sprocket12, Mar 23 '12 at 11:35
There may be chance that you are using the Master page in which this function may exist as it is shown in the source so you have to manually add this in your page. — Vishal Suthar, Mar 23 '12 at 11:42
Guys please see my update, problem is fixed, if anyone knows why it doesnt like that javascipt in the header please let me know. — sprocket12, Mar 23 '12 at 11:45
What is the Verify function doing? That may be where the problem originated. — Alex Morales, Mar 23 '12 at 11:49

score 3 · Answer 1 · edited May 23 '17 at 12:27

The problem is the default way ASP.net treats unknown browsers... such as the iPhone. Even though it would be nice to assume unknown browsers could use javascript... you can specify what capabilities that a browser has in the section of web.config or machine.config.

Check out http://slingfive.com/pages/code/browserCaps/ for an updated browsercaps config file for asp.net

Here is an example of a case to match GECKO Based Browsers (Netscape 6+, Mozilla/Firefox, ...)

Reference: this question and answer.

<case match="^Mozilla/5\.0 \([^)]*\) (Gecko/[-\d]+)(?'VendorProductToken' (?'type'[^/\d]*)([\d]*)/(?'version'(?'major'\d+)(?'minor'\.\d+)(?'letters'\w*)))?">
                    browser=Gecko
                    <filter>
                            <case match="(Gecko/[-\d]+)(?'VendorProductToken' (?'type'[^/\d]*)([\d]*)/(?'version'(?'major'\d+)(?'minor'\.\d+)(?'letters'\w*)))">
                                    type=${type}
                            </case>
                            <case> <!-- plain Mozilla if no VendorProductToken found -->
                                    type=Mozilla
                            </case>
                    </filter>
                    frames=true
                    tables=true
                    cookies=true
                    javascript=true
                    javaapplets=true
                    ecmascriptversion=1.5
                    w3cdomversion=1.0
                    css1=true
                    css2=true
                    xml=true
                    tagwriter=System.Web.UI.HtmlTextWriter
                    <case match="rv:(?'version'(?'major'\d+)(?'minor'\.\d+)(?'letters'\w*))">
                            version=${version}
                            majorversion=0${major}
                            minorversion=0${minor}
                            <case match="^b" with="${letters}">
                                    beta=true
                            </case>
                    </case>
            </case>

Can’t find variable __doPostBack

1 Answers1