How to save page settings for the next session?

Question

With my Greasemonkey script, I've added a checkbox. My idea is that if the checkbox is true do something, but if it is false do nothing.

I also want the checkbox to remember the user's last choice, so that if the user closes the webpage or browser, when he returns the checkbox is again true/false.

For example:

$('input[name=check0]').click(function(){
    $('#shoutbox_b').click();
});

In this example, I want check0 to be always true. But, when I reload the page it is false until I click the checkbox again.

Answer 1

Use GM_setValue() or localStorage to save the input state between page loads.

Here is a complete Greasemonkey script, using jQuery, that shows the process. It is for normal, static pages. (For AJAX-driven pages you would also use waitForKeyElements):

// ==UserScript==
// @name     _Save checkbox state between page visits
// @include  http://YOUR_SERVER.COM/YOUR_PATH/*
// @require  http://ajax.googleapis.com/ajax/libs/jquery/1.8.3/jquery.min.js
// @grant    unsafeWindow
// ==/UserScript==

//-- Get saved state:
var chk0wasChked    = (localStorage.getItem ('check0_state')  ==  "true");

//-- Get current state:
var chk0isChked     = $('input[name=check0]').prop ('checked');

/*-- If the states don't match, click the checkbox to synch them up.
    We need a small delay to avoid race conditions.
*/
setTimeout (setThenMonitorCheckboxState, 333);

function setThenMonitorCheckboxState () {
    if (chk0wasChked != chk0isChked) {
        unsafeWindow.$('input[name=check0]').click ();
    }

    //-- *After* the initial set, monitor & save any future state changes:
    $('input[name=check0]').click ( function () {
        var chk0isChked = $('input[name=check0]').prop ('checked');

        localStorage.setItem ('check0_state', chk0isChked);
    } );
}

---

Note: The question was not clear. If the original click handler for input[name=check0] was set by the target page. Use the code as above.

But, if the original click handler for input[name=check0] was set by the Greasemonkey script, then change unsafeWindow.$ to just $.