https://app.edubase.ch/sw/swPing.js

1/**
2 * Simple Service Worker Ping Script
3 * Sends periodic pings to keep the service worker alive
4 */
5
6(function () {
7    'use strict';
8
9    // Check if service worker is supported
10    if (!('serviceWorker' in navigator)) {
11        console.warn('Service Worker not supported');
12        return;
13    }
14
15    let pingInterval = null;
16    let missedPongs = 0;
17    const maxMissedPongs = 3;
18    const pingIntervalMs = 20000;
19
20    function sendPing() {
21        if (!navigator.serviceWorker.controller) {
22            console.warn('[SW Ping] No active Service Worker to ping');
23            missedPongs++;
24            return;
25        }
26
27        try {
28            const timestamp = Date.now();
29            navigator.serviceWorker.controller.postMessage({
30                action: 'ping',
31                timestamp: timestamp,
32            });
33
34            // Only increment missedPongs if we don't get a response
35            // We'll reset this when we receive a pong
36            const currentMissedPongs = missedPongs + 1;
37
38            if (currentMissedPongs >= maxMissedPongs) {
39                console.warn('[SW Ping] Multiple pings missed, attempting to recover...');
40                stopPing();
41                setTimeout(() => {
42                    startPing();
43                }, 1000);
44                missedPongs = 0;
45            } else {
46                missedPongs = currentMissedPongs;
47            }
48        } catch (error) {
49            console.error('[SW Ping] Error sending ping:', error);
50            missedPongs++;
51        }
52    }
53
54    function startPing() {
55        if (pingInterval) {
56            return;
57        }
58
59        pingInterval = setInterval(sendPing, pingIntervalMs);
60
61        // Send initial ping
62        sendPing();
63    }
64
65    function stopPing() {
66        if (pingInterval) {
67            clearInterval(pingInterval);
68            pingInterval = null;
69        }
70    }
71
72    function resetMissedPongs() {
73        missedPongs = 0;
74    }
75
76    // Listen for pong responses from service worker
77    navigator.serviceWorker.addEventListener('message', function (event) {
78        try {
79            const data = JSON.parse(event.data);
80            if (data && data.action === 'pong') {
81                missedPongs = 0;
82            }
83        } catch (error) {
84            console.error('[SW Ping] Error parsing message:', error);
85        }
86    });
87
88    // Handle user interactions to reset missed pongs
89    function onUserInteraction() {
90        resetMissedPongs();
91    }
92
93    const events = ['click', 'keydown', 'mousemove', 'scroll', 'touchstart'];
94    events.forEach((eventType) => {
95        document.addEventListener(eventType, onUserInteraction, {passive: true});
96    });
97
98    // Handle page visibility changes
99    document.addEventListener('visibilitychange', function () {
100        if (!document.hidden) {
101            resetMissedPongs();
102        }
103    });
104
105    if (document.readyState === 'loading') {
106        document.addEventListener('DOMContentLoaded', startPing);
107    } else {
108        startPing();
109    }
110
111    window.swPing = {
112        start: startPing,
113        stop: stopPing,
114        reset: resetMissedPongs,
115        getStatus: () => ({
116            isRunning: !!pingInterval,
117            missedPongs: missedPongs,
118            maxMissedPongs: maxMissedPongs,
119            interval: pingIntervalMs,
120        }),
121    };
122})();