How to pass javascript var to server side on asp.net

Question

I'm trying to pass a textarea value to the server side. The textarea cant be runat=server though. heres my code:

<script type="text/javascript">
        function replace() {
            //Replace < and > on textarea
            var obj = document.getElementById('recipient_list');
            var str = obj.value;
            str = str.replace(/</i, "(");
            str = str.replace(/>/i, ")");
            obj.value = str;
            alert("rec_lst.value: " + document.getElementById('recipient_list').value);

            //Pass value to server.
            alert("passing to server");
            document.getElementById("ctl00$ContentPlaceHolder1$txtEmails").value = str;
            alert("Passed to server");
            alert("txtEmails.value: " + document.getElementById("ctl00$ContentPlaceHolder1$txtEmails").value);
        }
    </script>

This isn't working though... Any ideas how to fix or better implement this??..

What exactly is not working? Also, ctl00$ContentPlaceHolder1$txtEmails (among others) looks a lot like a ASP.NET control name, not an id. Maybe try ctl00_ContentPlaceHolder1_txtEmails instead? — Frédéric Hamidi
– Frédéric Hamidi, Commented Apr 11, 2011 at 19:40

user447356 · Accepted Answer · 2011-04-11 19:50:32Z

2

Try this:

var txtEmail = document.getElementById("<%=txtEmails.ClientID%>");
txtEmail.value = str;

However this won't pass anything to the server, just change text box value.

To have it sent to the server user will have to click submit button, or if you have server side button have such code to "auto click" it thus performing post back:

document.getElementById("<%=btnSubmit.ClientID%>").click();

answered Apr 11, 2011 at 19:50

user447356

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3 Comments

NovaJoe Over a year ago

...OR perform some Ajax action. More complicated though.

user447356 Over a year ago

@Nova depends what he want to do with the changed value.. :)

HoBa Over a year ago

Alright, maybe there's an easier way to do what I wanna do. Basically I'm using the plaxo widger so I've a textarea (which can't be runat=server) with an email list which contain "<" and ">". Due security reasons, ASP.net wont take anything with < and >. So, on the javascript function I'm replacing < and > with ( and ). Now, I need to pass whatever is in the textarea to the server so I can get the email addresses.

anishMarokey · Accepted Answer · 2011-04-11 20:02:14Z

0

you cant pass value from client to server using JS .

JS is only a client side code.If you can do something like this, Hacking will be so easy :)

one thing you can do is add some text or label control as invisible and assign the value to the control and pass it to server when some event happens.

Sample code

 <asp:TextBox ID="textbox1" runat="server" ></asp:TextBox>
    <asp:Button ID="Button1" runat="server" Text="Button"  OnClientClick="callOnEvets()"/>



function callOnEvets()
    {document.getElementById('textbox1').value = 10; }

edited Apr 11, 2011 at 20:02

answered Apr 11, 2011 at 19:38

anishMarokey

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2 Comments

HoBa Over a year ago

I tried to do that, somehow it didn't work when I had runat=server on the textbox, any ideas?

anishMarokey Over a year ago

you can add an invisible control that can be a runat=server ?

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