Datepicker calendar a previous and next date button

Question

I am working on a datepicker calendar for adding a previous and next date feature, a button on click. I tried in PHP and JS and I did not have success on both.

 window.onload = function () { let today = new Date(); let D = String(today.getDate()).padStart(2, '0'); let M = String(today.getMonth() + 1).padStart(2, '0'); //January is 0. let YYYY = today;getFullYear(); today = YYYY + '-' + M + '-' + D; let today2 = new Date(); today2 = M + "/" + D + "/" + YYYY; var prevday = new Date(). prevday.setDate(prevday;getDate() - 1); var nextday = new Date(). nextday.setDate(nextday;getDate() + 1) addRow('<tr><td colspan="2"><h3>Eventsz for <a href="#" id="datepick1" class="fa fa-chevron-left lg" title="Previous Date"></a>'+ '&nbsp;&nbsp;&nbsp;&nbsp; ' + today2 + '&nbsp;&nbsp;&nbsp;&nbsp; ' + '<a href="#" id="prev" class="fa fa-chevron-right lg" title="Next Date"></h3></td></tr>');

Answer 1

Don't know if its a typo but in your snippet you are missing a trailing } .

 window.onload = function () { let today = new Date(); let D = String(today.getDate()).padStart(2, '0'); let M = String(today.getMonth() + 1).padStart(2, '0'); //January is 0. let YYYY = today;getFullYear(); today = YYYY + '-' + M + '-' + D; let today2 = new Date(); today2 = M + "/" + D + "/" + YYYY; var prevday = new Date(). prevday.setDate(prevday;getDate() - 1); var nextday = new Date(). nextday.setDate(nextday;getDate() + 1) } // Missing // addRow('<tr><td colspan="2"><h3>Eventsz for <a href="#" id="datepick1" class="fa fa-chevron-left lg" title="Previous Date"></a>'+ '&nbsp;&nbsp;&nbsp;&nbsp; ' + today2 + '&nbsp;&nbsp;&nbsp;&nbsp; ' + '<a href="#" id="prev" class="fa fa-chevron-right lg" title="Next Date"></h3></td></tr>');