JSFiddle - React, Tailwind, and code Playground

HTML

<span id="date"></span>

JavaScript

var d1 = new Date(2018, 07, 01) // date(year, month - 1, day)
days= -1; //# of days
d
var d2 = new Date(d1.setDate(d1.getDate() + days));
                       
document.getElementById('date').innerHTML = d2;