Formula field (date) and examples
The has field has standard date time search functions in Jira.
Formula (JavaScript): return date
The script must return a numeric representation of the date as a number or string of number for constructor new Date(value) doc.
new Date().getTime()or for example: 7 days after creation
issue.getCreated().getTime() + 7*24*60*60*1000
Date custom field + days(number) from another custom fields
This script returns the date of the specified field increased by the number of days from the second field.
var dateCustomFieldId = 10101;//Date picker
var daysCustomFieldId = 10200;//Number field
if(cfValues[dateCustomFieldId] != null){
cfValues[dateCustomFieldId].time + cfValues.getOrDefault(daysCustomFieldId, 0)*24*60*60*1000
}