The new Java Plug-In has abstracted the Java/JavaScript bridge between different web browsers. It is now strongly desired to support calling from JavaScript on a web page into objects of non-Java languages hosted on the JVM. It will be necessary to expose hooks to allow the run-time systems of these JVM-based languages to detect invocations, field accesses, etc. that they should handle; perform data type conversions; delegate down to default data type conversions already provided by the Java Plug-In; etc. The first consumer of this functionality will be the run-time system for JavaFX.