Reusable sharepoint javascript functions

//First we must call the EnsureSetup method
JSRequest.EnsureSetup(); 

itemId = JSRequest.QueryString["ItemId"];
var pagename = JSRequest.FileName;

 var pagepath = JSRequest.PathName;
LoginAsAnother(url, bUseSource);





url(string): the url of the page to which the new user has to be sent after login.

bUseSource(boolean): A boolean that indicates that the source will be added to the url, otherwise the source will be the window.location.href. This parameter is optional, default is false.