bootstrap-vue/src/utils/addEventListenerOnce.js

Quickly integrate Bootstrap 4 components with Vue.js

/**
 * Register and event to listen on specified element once.
 * @param {Element} element to listen on
 * @param {String} event to listen for
 * @param {Function} callback when event fires
 */
export default function addEventListenerOnce (el, evtName, callback) {
  function fnOnce () {
    el.removeEventListener(evtName, fnOnce)
    return callback.apply(null, arguments)
  }
  el.addEventListener(event, fnOnce)
}