Require field based on date comparison

This example uses the DATEADD and SETREQUIRED functions to compare today's date with the start_date date field. This example assumes start_date was entered in a previous version of the record, so we can listen to the load-record event, add 7 days to the start_date value and if the current date is a week or more later, we require the end_date field be filled out.

ON('load-record', function (event) {
  var today = new Date();
  if (today >= DATEADD($start_date, 7)) {
    SETREQUIRED('end_date', true);
  }
});

This works well in cases where you are revisiting an existing record, but you could also use validate-record to compare dates for the current version.

ON('validate-record', function (event) {
  var today = new Date();
  if (today >= DATEADD($start_date, 7)) {
    INVALID('End Date is required!');
  }
});