Plain javascript alternative to jQuery ready() - readyState and DOMContentLoaded

ready-function.js

// based on: https://www.techiediaries.com/javascript/pure-javascript-equivalent-or-alternative-to-jquery-ready/
// based on: https://stackoverflow.com/a/9899701/271985
function docReady(fn) {
  if (document.readyState !== 'loading'){
    fn();
  } else {
    document.addEventListener('DOMContentLoaded', fn);
  }
}

//**************
// usage:
docReady(myFunction);
// or
docReady(function() {
  // your code
});

ready-function.min.js

function docReady(d){"loading"!==document.readyState?d():document.addEventListener("DOMContentLoaded",d)}