Open Dlive sticker to a new tab with middle mouse button

dlive.js

// ==UserScript==
// @name     		Dlive
// @description Open sticker on dlive with middle mouse button to a new tab
// @version  		1
// @grant    		none
// @include  		/^https:\/\/dlive.tv\/.+$/
// @run-at   		document-end
// ==/UserScript==

'use strict';

function addClickHandler(elem) {
  elem.addEventListener('mousedown', (e) => {
    if (e.button === 1)
    	window.open(elem.src);
  });
}

function dlive(chat) {
  chat.querySelectorAll('.emote-img').forEach(e => addClickHandler(e));
  
  const o = new MutationObserver((mutationList) => {
  	for (const m of mutationList) {
      const sticker = m.addedNodes[0].querySelector('.emote-img');
      if (sticker)
        addClickHandler(sticker);
    }
  });
  o.observe(chat, { childList: true, attributes: true, subtree: true, });
}

const chatBody = document.querySelector('#chat-body');
if (chatBody) {
  dlive(chatBody);
}
else {
  const o = new MutationObserver((mutationList) => {
    for (const m of mutationList) {
      const chat = m.addedNodes[0].querySelector('#chat-body');
        if (chat) {
          dlive(chat);
        }
    }
  });
  o.observe(document.body, { childList: true, attributes: true, subtree: true, });
}