JSFiddle - React, Tailwind, and code Playground

JavaScript

// Add leading Characters to a string or number
function addLeadingChars(string, nrOfChars, leadingChar) {
	string = string + '';
	return Array(Math.max(0, (nrOfChars || 2) - string.length + 1)).join(leadingChar || '0') + string;
}

// Usage
var
	date = new Date(),
	month = addLeadingChars(date.getMonth() + 1),
	day = addLeadingChars(date.getDate());

console.log(date, month, day);