Detect Addition to localStorage/sessionStorage

localStorage.js

  sessionStorage.setItem = function (key, value) {
    var event = new Event("itemInserted");
    event.value = value; // Optional..
    event.key = key; // Optional..
    document.dispatchEvent(event);
    originalSetItem.apply(this, arguments);
  };
  var sessionStorageSetHandler = function (e) {
  console.log(e.key);
  console.log(e.value);
  };
  
  document.addEventListener("itemInserted", sessionStorageSetHandler, false);