Let’s suppose we have a blog built with Eleventy. And let’s further suppose that we want our URLs for our blog posts to be based on the publication date for the post; something like /blog/<year>/<month>/<day>/. Seems perfectly reasonable, right? There’s a footgun1 here. Any time we publish on a day whose date matches the month — 1 January, 2 February, 3 March, etc. — the <day> part of our URL is going to be stripped out and we’ll be left with /blog/<year>/<month>/.
