how often is Christmas on a Sunday?

 Joined my folks for Church stuff this Christmas day, a Sunday, and the minister mentioned we wouldn't have another Christmas Sunday until 2033!

Curious, I made up this jsitor to see which years had Christmas Sundays, and then what was the pattern.

So day of week for a certain date (I'm sure very similar for all post-Feb 28 days, and then probably roughly similar for days before) repeat every 5, 6, and 11 years, depending on if the leap day is with or against it and then sometimes skipped. 

It's nice to be able to compute this stuff out, though not as interesting as 2013's Thanksgiving on the First Day of Hanukkah - something said not to recur for 70,000 years. 

UPDATE: either jsitor isn't design for codepen-typing sharing (like, optimized for live sharing) or I'm doing something wrong, because my snippet went away. But I reconstructed the logic:

function getDayNameForDate(date){

return ['sun', 'mon', 'tue', 'wed', 'thu', 'fri', 'sat'][date.getDay()];

}

let lastYearWithXmasSun = 2022;

for(let year = 2023; year <= 2222; year++) {

const date = new Date(`December 25, ${year} 12:00:00`);

const dayName = getDayNameForDate(date);

if(dayName === 'sun'){

console.log(`${year}: ${year - lastYearWithXmasSun}`);

lastYearWithXmasSun = year;

}

}

In general, that refreshes my biases about depending on fewer external sites for my blogs. In particular I'm really said how many embedded videos on my blog have gone away when I look at it on this date feature... I mean many of the links are broken too but they're not as visible a scar. I bemoaned that process, and the disillusion about how a URL could/should be "forever", in November.