How to get first date and last date of the week from week number and year?

In JavaScript I want to get first date of the week and last date of the week by week number and year only.

For example if I my input is:

2(week),2012

Then my output should be:

2012-01-08 and 2012-01-14

Answer

Try this:

var year = 2012;
var week = 2;
var d = new Date("Jan 01, " + year + " 01:00:00");
var w = d.getTime() + 604800000 * (week - 1);
var n1 = new Date(w);
var n2 = new Date(w + 518400000)

console.log(n1);
console.log(n2);

n1 contains the first day of the week
n2 contains the last day of the week

As for the constants:
604800000 is one week in milliseconds
518400000 is six days