Part 21 of the series: "Extending bpmn-io Form-JS Beyond Its Limits"

Every extension in this series — the evaluators, validators, providers, renderers, file handlers — ultimately gets loaded into a form instance. Something has to create that instance, configure which modules it loads, and expose the capabilities that application code needs to call.

That something is CustomForm and CustomFormEditor .

These two classes are thin subclasses of Form-JS's Form and FormEditor . They don't reimagine the base classes — they add exactly what the extension system needs and nothing more. The _isRendered flag so consumers know when it's safe to interact with the form. The _pendingFilesRef store so file handling works across framework boundaries. The form.rendered event so evaluators know when the DOM exists.…