JSFiddle - React, Tailwind, and code Playground

HTML

<div id="test"></div>

JavaScript

function getMonth(mon){
   var monthNum = new Date(mon +" 1, 2012").getMonth()+1;
   return ("0" + monthNum).slice(-2);
}

[ 'January', 'February', 'March', 'April', 'May', 'June', 'July', 'August', 'September', 'October', 'November', 'December' ].forEach(function(m) {
    document.getElementById('test').innerHTML += (getMonth(m) + '<br/>');
});