let today = new Date().toISOString().slice(0, 10)
const startDate = '2021-04-15';
const endDate = today;
const diffInMs = new Date(endDate) - new Date(startDate)
const diffInDays = diffInMs / (1000 * 60 * 60 * 24);
alert( diffInDays );
function calculateDaysBetweenDates(date1, date2) {
var oneDay = 24 * 60 * 60 * 1000;
var date1InMillis = date1.getTime();
var date2InMillis = date2.getTime();
var days = Math.round(Math.abs(date2InMillis - date1InMillis) / oneDay);
return days;
}
const date1 = new Date('19/1/2021');
const date2 = new Date('20/1/2021');
const diffTime = Math.abs(date2 - date1);
const diffDays = Math.ceil(diffTime / (1000 * 60 * 60 * 24));
console.log(diffTime + " milliseconds");
console.log(diffDays + " days");
const dayDif = (date1, date2) => Math.ceil(Math.abs(date1.getTime() - date2.getTime()) / 86400000)
dayDif(new Date("2020-10-21"), new Date("2021-10-22"))
// Result: 366
const diffDays = (date, otherDate) => Math.ceil(Math.abs(date - otherDate) / (1000 * 60 * 60 * 24));
// Example
diffDays(new Date('2014-12-19'), new Date('2020-01-01')); // 1839
<input id="first" value="25/2/2021"/>
<input id="second" value="26/2/2021"/>