SFDC Message Factory This creates an object for use in any normal Salesforce page and a typical custom Visualforce page that allows you to easily set an error or information message, as well as clearing these messages.
Usage: Initialization var msg = sfdcMsg.createMessageFactory();
Set Error Message: msg.setErrorMessage('Error Message');
Set Info Message: msg.setInfoMessage('Info Message');
Clear Error Message: msg.clearErrorMessage();
Clear Info Message: msg.clearInfoMessage();
Clear All Messages: msg.clearMessages();