Detect Caps Lock in JavaScript

Kate Rose Mosley has a method for detecting caps lock in JavaScript. It's important to listen to keydown and keyup because browsers behave differently.

addEventListener("keydown", detectCapsLock)
addEventListener("keyup", detectCapsLock)

function detectCapsLock(e) {
  if (e.getModifierState("CapsLock")) {
    console.log("caps lock is on")
  } else {
    console.log("caps lock is off")
  }
}