Toggle fonts-loaded class

togglefontsloadedclass.js

// ==UserScript==
// @name        Toggle fonts-loaded
// @namespace   agaric
// @description Toggle fonts loaded
// @include     *.local
// @version     1
// @grant       none
// ==/UserScript==

(function(){
    'use strict'

  window.addEventListener('load', () => {
    addButton('toggle fonts-loaded', toggleFontsLoaded)
    })

    function addButton(text, onclick, cssObj) {
        cssObj = cssObj || {position: 'absolute', bottom: '7%', left:'4%', 'z-index': 3}
        let button = document.createElement('button'), btnStyle = button.style
        document.body.appendChild(button)
        button.innerHTML = text
        button.onclick = onclick
        Object.keys(cssObj).forEach(key => btnStyle[key] = cssObj[key])
        return button
    }

    function toggleFontsLoaded() {
        [...document.getElementsByTagName('html')].forEach(element => element.classList.toggle("fonts-loaded"))
    }

}())