JQuery: how to get the value of an ID from Master/Content page in ASP.NET

Question

i have this in my content page: but i am getting null value if i try $("#ctl00_cphMaster_CloseButton").

$(document).ready(function() {
    $("#ctl00_cphMaster_CloseButton").click(function() {
            jConfirm('Can you confirm this?', 'Confirmation Dialog', function(r) {
                if (r == true)
                    __doPostBack('CloseButton', '');
            });
            return false;
        });
    });
});

<uc1:ImageTextButton ID="CloseButton" runat="server" 
            ImageURL="Images/closeIcon.png"
            Enabled="True" Text="Close" 
            CausesValidation="false" onclick="CloseButton_Click" />

UPDATE:

i have tried like this:

$("#<%= CloseButton.ClientID %>").click(function() {

        jConfirm('Can you confirm this?', 'Confirmation Dialog', function(r) {
            if (r == true)
                __doPostBack('CloseButton', '');
        });
        return false;
    });
});

when i run my page it throws me an error with this code:

$("#ctl00_cphMaster_CloseButton").click(function() {

        jConfirm('Can you confirm this?', 'Confirmation Dialog', function(r) {
            if (r == true)
                __doPostBack('CloseButton', '');
        });
        return false;
    });

it means it got the right id but why is it throwing an error complaining about null

Microsoft JScript runtime error: 'null' is null or not an object

UPDATE:

KP Suggestion:

$("#<%= CloseButton.ClientID %>").click(function() { 
             alert("yes");
       }); 
});

Answer 1

Have you tried to use the ClientID-Property of the button-control?

$("#<%= CloseButton.ClientID %>")

Answer 2

I'd go with $("[id$=CloseButton]") which matches elements which end with CloseButton