Cannot call Javascript function from ASP.NET 4 onclick event button

Question

when i call the javascript function from asp:button onclick event, i got this error message

HTML

 <asp:Button ID="btnFromCalOpen" runat="server" Text=" &gt; " onclick="ShowCal()" CssClass = "SElementHide" /> 

Javascript

 function ShowCal() { var elem = document.getElementById('MainContent_CalendarFrom'); if (elem.visibility = "hidden" ) { elema.style.visibility = "visible"; elema.style.display = "block"; } else { elema.style.visibility = "hidden"; elema.style.display = "none"; } } 

Error Compiler Error Message: BC30456: "ShowCal" is not a member of "ASP.default_aspx".

Please, help

Answer 1

Use OnClientClick so that your ASP.NET button OnClientClick JavaScript method before OnClientClick your server-side method. OnClick specifies how to work on the server side.

 <asp:Button ID="btnFromCalOpen" runat="server" Text=" &gt; " CssClass = "SElementHide" OnClientClick="ShowCal()" /> 

Answer 2

Have you tried the OnClientClick property?

http://msdn.microsoft.com/en-us/library/system.web.ui.webcontrols.button.onclientclick.aspx

Also, this does not look right:

 if (elem.visibility = "hidden") 

Should be closer to:

 if (elem.style.visibility == "hidden") 

Are you also looking for a button to prevent mail from being sent? Then return false to your ShowCal javascript function.

Answer 3

use OnClientClick . onclick is for the server side handler.

you also need to check elem.style.visibility .

also you create elem in your js function and then try to access elema .