JSFiddle - React, Tailwind, and code Playground

JavaScript

function getDateOfISOWeek(w, y) {
    var simple = new Date(Date.UTC(y, 0, 1 + (w - 1) * 7));
    var dow = simple.getUTCDay();
    var ISOweekStart = simple;
    if (dow <= 4)
        ISOweekStart.setUTCDate(simple.getUTCDate() - simple.getUTCDay() + 1);
    else
        ISOweekStart.setUTCDate(simple.getUTCDate() + 8 - simple.getUTCDay());
    return ISOweekStart;
}

function getEndOfISOWeek(d) {
		var endOfISOWeek = new Date(d.getTime());
    endOfISOWeek.setUTCDate(endOfISOWeek.getUTCDate() + 6);
    endOfISOWeek.setUTCHours(23);
    endOfISOWeek.setUTCMinutes(59);
    endOfISOWeek.setUTCSeconds(59);
    return endOfISOWeek;
}

var startOfWeek = getDateOfISOWeek(29,2016);
var endOfWeek = getEndOfISOWeek(startOfWeek);

console.log(startOfWeek.toUTCString(), endOfWeek.toUTCString());