About a year ago, when I was first getting into Node.js, I wrote this quick web app called "flag-at-half-mast". It's a pretty straightforward web app - it tells you whether or not the US flag is supposed to be at half staff/half mast, and what reason.
For this project, I used a small RSS parser module that takes the latest entries into the White House Presidential Proclamation Log's RSS feed (yes, it turns out the White House still uses RSS. Who knew?) and checks to see whether there is any indication that the White House, Congress, or someone else ordered flags to be flown at half staff.
As I was first getting into Node when I wrote this, the code is pretty inefficient. It polls the RSS feed every time it's called up, and because it works on just searching the RSS for relevant keywords, it can return false positives or miss some proclamations entirely. If you want to take a look at it, you can check out the source code at https://github.com/Nomikxyz/flag-at-half-mast. The service itself is available at https://flag.nomik.xyz.
I'm currently working on a more efficient version of this app that has email/SMS notifications.