JSFiddle - React, Tailwind, and code Playground

by Felipe Alfaro

HTML

<div id="date">

</div>

JavaScript

function paddingDigits(number, digits) {
    return new Array(Math.max(digits - String(number).length + 1, 0)).join(0) + number;
}


function dateMath( $yyyymmdd , addOrRemoveDays ){
    var dateString = $yyyymmdd.split('-'),
        dateObject =  new Date(dateString),
        days = new Number(addOrRemoveDays);
    dateObject.setDate(dateObject.getDate()+days);

    var YYYY = paddingDigits( dateObject.getFullYear().toString(), 4 ),
        MM = paddingDigits( (dateObject.getMonth()+1).toString(), 2 ),
        DD = paddingDigits( dateObject.getDate().toString(), 2 );

    document.getElementById('date').innerHTML = YYYY+'-'+MM+'-'+DD;
}


dateMath('2016-02-15','-5');