There isn't such a function built-in, though something like it (a doNotUnderstand functionality to call a default function instead of throwing an error if the requested field isn't found on an object) has been proposed as a future addition to the JavaScript standard.
IgorPartola's example code won't intervene in the usual function-call process; rather, it provides a tacked-on means of simulating message sending behavior that ought to be included in the language's syntax under Kay's definition of OO. With this convention, you'd never call bar(), or any other method, directly; you'd call handle to send a 'bar' message to the object instead. Then, if you send a message the object doesn't understand, handle() can route it properly.
IgorPartola's example code won't intervene in the usual function-call process; rather, it provides a tacked-on means of simulating message sending behavior that ought to be included in the language's syntax under Kay's definition of OO. With this convention, you'd never call bar(), or any other method, directly; you'd call handle to send a 'bar' message to the object instead. Then, if you send a message the object doesn't understand, handle() can route it properly.