Number of days in month could vary based on month and year value. From https://www.timeanddate.com/calendar/months/
Each month has either 28, 30, or 31 days during a common year, which has 365 days. During leap year, which occur nearly every 4 years, we add an extra (intercalary) day, Leap Day, on 29 February, making leap years 366 days long.
Datepicker in drupal is rendered as separate select elements for day, month and year by default which makes it difficult to set a default value if we want to set it to some string value, eg. today, +2 months, etc. This page is to check how we can set default value for datepicker using a simple jQuery.
Consider you have the above string value. If you are sending this value from a php code, convert it to a date format using strtotime().
