Как-то так можно
var now = new Date(),
time = now.getTime(),
date = now.getDate(),
day = now.getDay(),
friday = [];
for(var i = 0, week = 0; i < 5; i++, week += 7) {
var d = new Date(time);
d.setDate(date + week + (5 - day) % 7)
friday.push(d);
}
console.log(friday);