JSFiddle - React, Tailwind, and code Playground

by grant

HTML

<script src="http://ajax.microsoft.com/ajax/jquery.validate/1.7/jquery.validate.js"></script>
<link rel="stylesheet" href="http://ajax.googleapis.com/ajax/libs/jqueryui/1.8.4/themes/ui-lightness/jquery-ui.css">

<div class="pad">
Add leading zeros to javascript date
</div>
<div class="pad" id="zero">
Add leading zeros to javascript date
</div>
<p>
get next monday
</p>
<div id="mon">
</div>
<div id="date">
</div>
<div id="wkd">
</div>
<div id="any">
</div>

CSS

.pad {
      margin: 0px 0px 0px 15px;
}
body {
      margin: 15px;
}

JavaScript

var myDate = new Date();
var myDateString;

myDate.setDate(myDate.getDate() + 2);

myDateString = ('0' + myDate.getDate()).slice(-2) + '/' + ('0' + (myDate.getMonth()+1)).slice(-2) + '/' + myDate.getFullYear();
myHourString = ('0' + myDate.getHours()).slice(-2)
console.log(myHourString)
console.log({myDateString})
z = document.getElementById('zero')
z.innerHTML = (myHourString)

// next monday
var d = new Date();
d.setDate(d.getDate() + (7-d.getDay())%7+1);
myDateString = ('0' + myDate.getDate()).slice(-2)
myHourString = ('0' + d.getHours()).slice(-2)
//console.log('hour ' + myHourString)

function getNextDayOfTheWeek(dayName, excludeToday = true, refDate = new Date()) {
    const dayOfWeek = ["sun","mon","tue","wed","thu","fri","sat"]
                      .indexOf(dayName.slice(0,3).toLowerCase());
    if (dayOfWeek < 0) return;
    refDate.setHours(12,0,0,0);
    refDate.setDate(refDate.getDate() + +!!excludeToday + 
                    (dayOfWeek + 7 - refDate.getDay() - +!!excludeToday) % 7);
    return refDate;
}

console.log("Next is: " + getNextDayOfTheWeek("Monday", false));
m = document.getElementById('any')
m.innerHTML = ("Next is: " + getNextDayOfTheWeek("Wednesday", false));

var d = new Date();
//d.setDate(d.getDate() + (7-d.getDay())%7+1);
//console.log(d.toLocaleString());
var next = (d.toLocaleString())
console.log(next)
m = document.getElementById('mon')
m.innerHTML = (next)
//document.write(d.toGMTString()+"<br>"+d.toLocaleString());
var dayo = d.toLocaleDateString(); 
dt = document.getElementById('date')
dt.innerHTML = (dayo)

var wkd = d.getDay(); 
dt = document.getElementById('wkd')
dt.innerHTML = ("weekday " + wkd)