Function off

Sortable.js:140–142

(el, event, fn)

    el.addEventListener(event, fn, !IE11OrLess && captureMode);
  }
  function off(el, event, fn) {
    el.removeEventListener(event, fn, !IE11OrLess && captureMode);
  }
  function matches( /**HTMLElement*/el, /**String*/selector) {
    if (!selector) return;
    selector[0] === '>' && (selector = selector.substring(1));