text: import Vue from 'vue';
  const isServer = Vue.prototype.$isServer;
  
  /* istanbul ignore next */
  export const on = (function() {
      if (!isServer && document.addEventListener) {
          return function(element, event, handler) {
              if (element && event && handler) {
                  element.addEventListener(event, handler, false);
              }
          };
      } else {
          return function(element, event, handler) {
              if (element && event && handler) {
                  element.attachEvent('on' + event, handler);
              }
          };
      }
  })();
  
  /* istanbul ignore next */
  export const off = (function() {
      if (!isServer && document.removeEventListener) {
          return function(element, event, handler) {
              if (element && event) {
                  element.removeEventListener(event, handler, false);
              }
          };
      } else {
          return function(element, event, handler) {
              if (element && event) {
                  element.detachEvent('on' + event, handler);
              }
          };
      }
  })();