How to call Telerik radalert from external JavaScript in ASP.Net master page -

i need show message using radalert in content pages associated master page.

i not able add javascript code master page, had add below specified code in external javascript file.

when below specified code added content page, displays message before session expires. javascript code:

 var sessiontimeoutwarning = "1";  var sessiontimeout = "2";  var timeonpageload = new date();  settimeout('redirecttowelcomepage()', parseint(sessiontimeout) * 60 * 1000);   function redirecttowelcomepage() {         var message = "session expired. redirecting login page";         radalert(message, 320, 100, "information message");         window.location = "login.aspx"     }    

but when code added external javascipt file can implemented in pages dependent on master page gives "unable property 'radalert' of undefined or null reference" error @ radalert

if accessing radcontrols external javascript. should aware of parameters function..

for example :

function open() { window.open("hello world", 320, 100, "information message"); } 

the above script not same radcontrols. need add parameters

function open(sender, args) { radalert("hello world", 320, 100, "information message"); }