list listener on a page js

1function listAllEventListeners() {
2  const allElements = Array.prototype.slice.call(document.querySelectorAll('*'));
3  allElements.push(document);
4  allElements.push(window);
5
6  const types = [];
7
8  for (let ev in window) {
9    if (/^on/.test(ev)) types[types.length] = ev;
10  }
11
12  let elements = [];
13  for (let i = 0; i < allElements.length; i++) {
14    const currentElement = allElements[i];
15    for (let j = 0; j < types.length; j++) {
16      if (typeof currentElement[types[j]] === 'function') {
17        elements.push({
18          "node": currentElement,
19          "type": types[j],
20          "func": currentElement[types[j]].toString(),
21        });
22      }
23    }
24  }
25
26  return elements.sort(function(a,b) {
27    return a.type.localeCompare(b.type);
28  });
29}