JSFiddle - React, Tailwind, and code Playground

HTML

<input type="text" id="password"></input>

JavaScript

function capLock(e) {
    kc = e.keyCode ? e.keyCode : e.which;
    sk = e.shiftKey ? e.shiftKey : ((kc == 16) ? true : false);
    if (((kc >= 65 && kc <= 90) && !sk) || ((kc >= 97 && kc <= 122) && sk)) console.log('caps lock on')
    else console.log('caps lock off');
}

$('#password').on('keypress', function (e) {
    capLock(e)
});