Auto-close the miniplayer and remove the miniplayer button on the player

autoclose-youtube-miniplayer.user.js

// ==UserScript==
// @name        Auto-close YouTube miniplayer
// @namespace   Violentmonkey Scripts
// @match       https://www.youtube.com/*
// @grant       none
// @version     1.0
// @author      Frellwit
// @description Auto-close the miniplayer and remove the miniplayer button on the player
// ==/UserScript==

function clickButton(selector){
  let elm = document.querySelectorAll(selector)[0];
  if (elm){ elm.click(); }
}

function addStyle(styleString) {
  const style = document.createElement('style');
  style.textContent = styleString;
  document.head.append(style);
}

function autoCloseMP() {
  // autoclick the close button on the miniplayer when the progressbar is finished
  // yt-navigate-finish would be better, but it seems to be too fast
  document.addEventListener('transitionend', function(e) {
    if (document.getElementById('progress') !== null) {
      if (e.target.id === 'progress') {
        clickButton('.ytp-miniplayer-close-button');
      }
    }
  });
  // hide the miniplayer icon
  addStyle(`.ytp-miniplayer-button {display:none!important;}`);
}
autoCloseMP();