Add an input for custom duration of the game
// ==UserScript==
// @name Custom time for arithmetic.zetamac.com
// @namespace http://tampermonkey.net/
// @version 0.2
// @description Add an input for custom duration of the game
// @author Anakojm
// @match http*://arithmetic.zetamac.com/
// @icon https://www.google.com/s2/favicons?sz=64&domain=zetamac.com
// @grant none
// @license GPL
// ==/UserScript==
(function() {
'use strict';
// Remove dropdown
document.querySelector("div#welcome form.game-options p select").remove()
// Create a new input element
let input=document.createElement("Input")
input.placeholder="Time (s)";
// The website is looking for the content of the duration element
input.name="duration";
// Append the new input to the wepbage
document.querySelector("div#welcome form.game-options p").append(input)
})();