Mojo.requireElement(expectedElement, message, messageProperties)

Writes an error to the log and throws an exception if expectedElement fails the Prototype isElement method. Returns String containing the error message written to the log.

Parameter	Type	Description
expectedElement	Object	Object to be checked to be a element.
message	String	Custom message to use if the assertion fails. Message will be run through template evaluation against messageProperties so you can include details of the assertion failure in the message.
messageProperties	Object	Object containing values to use with template evaluation.

Example usage:

Mojo.View.makeFocusable = function(targetElement) {
    Mojo.requireElement(targetElement, "Mojo.View.makeFocusable requires an element.");
    targetElement.setAttribute("tabindex", "0");
};