JSFiddle - React, Tailwind, and code Playground
HTML
<script src="https://momentjs.com/downloads/moment.js"></script>JavaScript
const input = "juni 2018";
const output = moment(input, "MMMM YYYY");
console.log('Start of the month:', output.startOf('month').format('DD.MM.YYYY'));
console.log('End of the month:', output.endOf('month').format('LL'));