I needed this code to create a TextExpander snippet that gives me the current calendar week in the format "3/2021".
```
function ISO8601_week_no(dt) {
var tdt = new Date(dt.valueOf());
var dayn = (dt.getDay() + 6) % 7;
tdt.setDate(tdt.getDate() - dayn + 3);
var firstThursday = tdt.valueOf();
tdt.setMonth(0, 1);
if (tdt.getDay() !== 4) {
tdt.setMonth(0, 1 + ((4 - tdt.getDay() + 7) % 7));
}
return 1 + Math.ceil((firstThursday - tdt) / 604800000);
}
date = new Date();
week = ISO8601_week_no(date);
year = date.getFullYear();
`${week}/${year}`;
```
Tags: [[Javascript]]