JSFiddle - React, Tailwind, and code Playground
by kdrdgn
HTML
<input type="text">
JavaScript
document.addEventListener('keydown', function(event) {
/* See https://developer.mozilla.org/en-US/docs/Web/API/KeyboardEvent/getModifierState
This function is supported in Firefox & MS Edge, webkit browsers
will be supported (soon) */
var caps = event.getModifierState && event.getModifierState('CapsLock');
console.log(caps); // true when you press the keyboard CapsLock key
});