https://www.bedburg.de/city_data/assets/336/sidebar.js

1// set the localStorag.bs_status and localStorag.bg_image by the class of the clicked button
2function set_bg_status( buttonElement ){
3    if( buttonElement.hasClass("hide_body_bg") ){
4        $('body').addClass("no_bg_image");
5        if (storageAvailable('localStorage')) {
6            localStorage.setItem( 'bg_status', "hide" );
7        }
8        $('body').addClass("no_bg_image");
9    } else {
10        $('body').removeClass("no_bg_image");
11        if (storageAvailable('localStorage')) {
12            localStorage.setItem( 'bg_status', "show" );
13        }
14    }
15}
16
17function storageAvailable(type) {
18    /* feature detection for storage types
19     * https://developer.mozilla.org/en-US/docs/Web/API/Web_Storage_API/Using_the_Web_Storage_API
20     */
21    var storage;
22    try {
23        storage = window[type];
24        var x = '__storage_test__';
25        storage.setItem(x, x);
26        storage.removeItem(x);
27        return true;
28    }
29    catch(e) {
30        return e instanceof DOMException && (
31            // everything except Firefox
32            e.code === 22 ||
33            // Firefox
34            e.code === 1014 ||
35            // test name field too, because code might not be present
36            // everything except Firefox
37            e.name === 'QuotaExceededError' ||
38            // Firefox
39            e.name === 'NS_ERROR_DOM_QUOTA_REACHED') &&
40            // acknowledge QuotaExceededError only if there's something already stored
41            (storage && storage.length !== 0);
42    }
43}
44
45$(function(){
46    // check and set the local storage default values für bg_change
47    if (storageAvailable('localStorage')) {
48        var current_bg_state = localStorage.getItem( 'bg_status' );
49
50        if( current_bg_state === null ){
51            localStorage.setItem( 'bg_status', "show" );
52        }else if( current_bg_state == "hide"){
53            $('body').addClass("no_bg_image");
54        }
55    }
56
57    // EVENT LISTENER
58    // click of bg change buttons
59    $("#sidebar_bg_change a.show_body_bg, #sidebar_bg_change a.hide_body_bg").click( function(){ 
60        set_bg_status( $(this) );
61        return false;
62    });
63});