Javascript error in form client side validation script when the form class is namespaced

The validation script generated by MoodleQuickForm::getValidationScript() uses the form name in the javascript function name. The form name is generated by moodleform::get_form_identifier() as the class name. With namespaced classes the form name may contain backslashes, as in

mod_dataform\pluginbase\entriesform

but javascript doesn't like it and fails.

MoodleQuickForm::getValidationScript() should make sure the form name is javascript valid and escape if needed.

Workaround: Override moodleform::get_form_identifier() in your namespaced form class to return an identifier without the backslashes.