Mojo.assertDefined(value, message, messageProperties)

Writes an error to the log if value evaluates to undefined. Returns String containing the error message written to the log.

Parameter	Type	Description
value	Object	Value that must not evaluate to undefined.
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.Event.listen=function listen(target,type,handlerFunction,useCapture){
  Mojo.assertDefined(target,"Mojo.Event.listen: 'target' parameter must be defined.");
  Mojo.assertString(type,"Mojo.Event.listen: 'type' parameter must be a string.");
  Mojo.assertFunction(handlerFunction,"Mojo.Event.listen: 'handlerFunction' parameter must be a function.");
  target.addEventListener(type,handlerFunction,!!useCapture);
};