There is no built-in recurrence support in the JavaScript version. The recurrence needs to be implemented on the server side and the implementation will be platform-specific.
If you only work with a limited set of recurrence rules, you may be able to implement it yourself. However, the recurrence can also get very complex, especially if you need to support exceptions from the rule (modify or delete individual occurrences).
On the client-side, the library will provide tools to add the support (e.g. you can display an icon indicating a recurring event) but you need to supply a complete list of individual occurrences/events.