Round moment.js object time to nearest 30 minute interval

Edit 2021 : easiest solution

const start = moment('2018-12-08 09:42');
const remainder = 30 - (start.minute() % 30);
 
const dateTime = moment(start).add(remainder, "minutes").format("DD.MM.YYYY, h:mm:ss a");

console.log(dateTime);

<script src="https://cdnjs.cloudflare.com/ajax/libs/moment.js/2.20.1/moment.min.js"></script>

Million ways to do this. You don't need moment.js really. Anyway, here is one.

Based on @Volune and @Cabloo answers and comments, an updated version can look like:

function round(date, duration, method) {
    return moment(Math[method]((+date) / (+duration)) * (+duration)); 
}

Which then can be used like:

var date = moment();
var roundedDate = round(date, moment.duration(15, "minutes"), "ceil");

A generic solution:

var ROUNDING = 30 * 60 * 1000; /*ms*/
start = moment();
start = moment(Math.ceil((+start) / ROUNDING) * ROUNDING);
start.format("D YYYY, h:mm:ss a");

You can change ROUNDING from 30 minutes to whatever you want, and change Math.ceil by Math.round or Math.floor if you want another way to round the value.