I am intereted in seeing a sample Java Script  to include on HTML page to process the JSON returned by  https://www.hebcal.com/yahrzeit

I used the VBA code in a previous Excel VBA application and it worked but was a lot to maintain.  I would like to use WEBAPIs and use  XMLHTTP calls in the VBA instead.  I am looking for the syntax and I think the Greg to Heb and reverse calls are obvious.   But I am looking for a call that is the functional equivalent of IsLeap in the VBA to determine if a Hebrew Year is or isn't a leap year without some complex code to figure out if Adar II is i the current year.