Excecuting a Javascript once per browser session (window)

Question

I have a simple Javascript code I want to run once per browser session, in a given website.

To clarify:

1. I open a browser session (window), say, Firefox.
2. I go to a certain webpage matched in Greasemonkey (say, google.com).
3. My script runs.
4. I fully refresh the wepbage (CTRL+F5), and the script no longer runs because it runs only once per session.

How can this be done? I mean, how can a simple script consisted only of one function, could be limited to run only once in a browser session, in a particular website matched in Greasemonkey?

Answer 1

You can use LocalStorage to do that. I have the whole logic explained in the comments.

if (typeof(Storage) !== "undefined") {
  // First timer
  if (!localStorage.getItem("oldUser")) {
    localStorage.setItem("oldUser", true);
    executeYourCode();
  }
} else {
  // Sorry! No Web Storage support..
  // Use the above cookie method.
}

Answer 2

Use window.localStorage to set a parameter isCalled = true

Here docs https://developer.mozilla.org/en/docs/Web/API/Window/localStorage