storage-event.js

(function() {
  if (window['StorageEvent'].name === 'StorageEvent') {
    return;
  }

  var _setItem = window.sessionStorage.setItem;
  Object.getPrototypeOf(window.sessionStorage).setItem = function(key, value) {
    _setItem.call(this, key, value);
    document.dispatchEvent(new CustomEvent('storage', { bubbles: true, composed: true, detail: { key: key, value: value } }));
  }
  
})();