How to attach data array to calendar array?

Question

JavaScript

something like an organizer:
1) There is an array of events for each element of which, among all the properties, there is a deadline date property.
2) There is an array of dates for the graphical construction of the calendar.
How to attach the first to the 2nd array? That is, it is not easy to sort array 1 by date, but if there is no event for a certain date, then in array 2 this element does not have an event, but there is a date.