-
Notifications
You must be signed in to change notification settings - Fork 0
/
Copy pathBasicServiceWorkerSample.html
271 lines (222 loc) · 16.9 KB
/
BasicServiceWorkerSample.html
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
44
45
46
47
48
49
50
51
52
53
54
55
56
57
58
59
60
61
62
63
64
65
66
67
68
69
70
71
72
73
74
75
76
77
78
79
80
81
82
83
84
85
86
87
88
89
90
91
92
93
94
95
96
97
98
99
100
101
102
103
104
105
106
107
108
109
110
111
112
113
114
115
116
117
118
119
120
121
122
123
124
125
126
127
128
129
130
131
132
133
134
135
136
137
138
139
140
141
142
143
144
145
146
147
148
149
150
151
152
153
154
155
156
157
158
159
160
161
162
163
164
165
166
167
168
169
170
171
172
173
174
175
176
177
178
179
180
181
182
183
184
185
186
187
188
189
190
191
192
193
194
195
196
197
198
199
200
201
202
203
204
205
206
207
208
209
210
211
212
213
214
215
216
217
218
219
220
221
222
223
224
225
226
227
228
229
230
231
232
233
234
235
236
237
238
239
240
241
242
243
244
245
246
247
248
249
250
251
252
253
254
255
256
257
258
259
260
261
262
263
264
265
266
267
268
269
270
<!doctype html>
<!--
Copyright 2016 Google Inc. All Rights Reserved.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
-->
<html lang="en">
<head>
<meta charset="utf-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="description" content="Sample illustrating the use of Basic Service Worker.">
<meta name="viewport" content="width=device-width, initial-scale=1">
<title>Basic Service Worker Sample</title>
<script>
// Add a global error event listener early on in the page load, to help ensure that browsers
// which don't support specific functionality still end up displaying a meaningful message.
window.addEventListener('error', function(error) {
if (ChromeSamples && ChromeSamples.setStatus) {
console.error(error);
ChromeSamples.setStatus(error.message + ' (Your browser may not support this feature.)');
error.preventDefault();
}
});
</script>
<link rel="icon" href="../../images/favicon.ico">
<link rel="stylesheet" href="main.css">
<link rel="stylesheet" href="styles.css">
</head>
<body>
<h1>Basic Service Worker Sample</h1>
<p class="availability">
Available in <a target="_blank" href="https://www.chromestatus.com/feature/6561526227927040">Chrome 40+</a> |
<a target="_blank" href="https://github.com/googlechrome/samples/blob/gh-pages/service-worker/basic/">View on GitHub</a> |
<a target="_blank" href="https://www.chromestatus.com/samples">Browse Samples</a>
</p>
<h3>Background</h3>
<p>
This sample demonstrates a basic service worker that could be used as-is, or
as a starting point for further customization.
</p>
<h4>What It Does</h4>
<ul>
<li>
Precaches the HTML, JavaScript, and CSS files needed to display this page offline.
(Try it out by reloading the page without a network connection!)
</li>
<li>Cleans up the previously precached entries when the cache name is updated.</li>
<li>Intercepts network requests, returning a cached response when available.</li>
<li>
If there's no cached response, fetches the response from the network and
adds it to the cache for future use.
</li>
</ul>
<p>
You can confirm the service worker's behavior using the
<a href="https://developers.google.com/web/tools/chrome-devtools/debug/progressive-web-apps/">Application panel</a>
of Chrome's DevTools.
</p>
<h4>What It Doesn't Do</h4>
<ul>
<li>
Automatically version any of the precached resources.<br>
<em>
You must manually update the <code>CACHES.PRECACHE</code> name to pick up
new versions after updating anything!
</em>
</li>
<li>
Cache-bust the precaching requests.<br>
<em>
The <code>cache.addAll()</code> call may be fulfilled with responses from
the HTTP cache, depending on the HTTP caching headers you use. If you
are using
<a href="https://jakearchibald.com/2016/caching-best-practices/">HTTP caching</a>
and unversioned resources, it can be safer to
<a href="https://github.com/GoogleChrome/samples/blob/5c20f8d74d890fad3d867747d2c3fc853727700c/service-worker/prefetch/service-worker.js#L56">cache-bust</a>
your precaching requests.
</em>
</li>
<li>
Refresh the entries in the runtime cache.<br>
<em>
Once an entry is added to the runtime cache, it's used indefinitely,
without consulting the network to check for updates. If your runtime cache
is used for resources that might be updated, a different strategy, like
<a href="https://jakearchibald.com/2014/offline-cookbook/#stale-while-revalidate">stale-while-revalidate</a>
could be more appropriate.
</em>
</li>
<li>
Clean out the runtime cache.<br>
<em>
The runtime cache will grow as new resource URLs are requested. In this
example, there are only 5 different images that might be loaded, so the
cache size isn't a concern. If your web app might request an arbitrary
number of unique resource URLs, then using a library like
<a href="https://github.com/GoogleChrome/sw-toolbox"><code>sw-toolbox</code></a>
which provides
<a href="https://github.com/GoogleChrome/sw-toolbox/tree/master/recipes/cache-expiration-options">cache-expiration</a>
is recommended.
</em>
</li>
</ul>
<h3>Live Demo</h3>
<p>
The following demo illustrates the service worker's runtime caching by loading
images in response to clicking the button below.
</p>
<p>
The first time a given image is requested, the service worker will be load it
from the network, but each subsequent time, it will be retrieved from the cache.
</p>
<label for="icons">Icons:</label>
<select id="icons">
<option value="icons/ic_create_new_folder_black_48dp.png">New Folder</option>
<option value="icons/ic_file_upload_black_48dp.png">File Upload</option>
<option value="icons/ic_folder_black_48dp.png">Closed Folder</option>
<option value="icons/ic_folder_open_black_48dp.png">Open Folder</option>
<option value="icons/ic_folder_shared_black_48dp.png">Shared Folder</option>
</select>
<button id="show">Show Icon</button>
<div id="container"></div>
<script>
if ('serviceWorker' in navigator) {
navigator.serviceWorker.register('service-worker.js');
}
document.querySelector('#show').addEventListener('click', () => {
const iconUrl = document.querySelector('select').selectedOptions[0].value;
let imgElement = document.createElement('img');
imgElement.src = iconUrl;
document.querySelector('#container').appendChild(imgElement);
});
</script>
<h3>JavaScript Snippet</h3>
<figure class="highlight"><pre><code class="language-js" data-lang="js"><span class="k">if</span> <span class="p">(</span><span class="s1">'serviceWorker'</span> <span class="k">in</span> <span class="nx">navigator</span><span class="p">)</span> <span class="p">{</span>
<span class="nx">navigator</span><span class="p">.</span><span class="nx">serviceWorker</span><span class="p">.</span><span class="nx">register</span><span class="p">(</span><span class="s1">'service-worker.js'</span><span class="p">);</span>
<span class="p">}</span>
<span class="nb">document</span><span class="p">.</span><span class="nx">querySelector</span><span class="p">(</span><span class="s1">'#show'</span><span class="p">).</span><span class="nx">addEventListener</span><span class="p">(</span><span class="s1">'click'</span><span class="p">,</span> <span class="p">()</span> <span class="o">=></span> <span class="p">{</span>
<span class="kr">const</span> <span class="nx">iconUrl</span> <span class="o">=</span> <span class="nb">document</span><span class="p">.</span><span class="nx">querySelector</span><span class="p">(</span><span class="s1">'select'</span><span class="p">).</span><span class="nx">selectedOptions</span><span class="p">[</span><span class="mi">0</span><span class="p">].</span><span class="nx">value</span><span class="p">;</span>
<span class="kd">let</span> <span class="nx">imgElement</span> <span class="o">=</span> <span class="nb">document</span><span class="p">.</span><span class="nx">createElement</span><span class="p">(</span><span class="s1">'img'</span><span class="p">);</span>
<span class="nx">imgElement</span><span class="p">.</span><span class="nx">src</span> <span class="o">=</span> <span class="nx">iconUrl</span><span class="p">;</span>
<span class="nb">document</span><span class="p">.</span><span class="nx">querySelector</span><span class="p">(</span><span class="s1">'#container'</span><span class="p">).</span><span class="nx">appendChild</span><span class="p">(</span><span class="nx">imgElement</span><span class="p">);</span>
<span class="p">});</span></code></pre></figure>
<h3>Service Worker's JavaScript</h3>
<figure class="highlight"><pre><code class="language-js" data-lang="js"><span class="cm">/*
Copyright 2016 Google Inc. All Rights Reserved.
Licensed under the Apache License, Version 2.0 (the "License");
you may not use this file except in compliance with the License.
You may obtain a copy of the License at
http://www.apache.org/licenses/LICENSE-2.0
Unless required by applicable law or agreed to in writing, software
distributed under the License is distributed on an "AS IS" BASIS,
WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
See the License for the specific language governing permissions and
limitations under the License.
*/</span>
<span class="c1">// Names of the two caches used in this version of the service worker.</span>
<span class="c1">// Change to v2, etc. when you update any of the local resources, which will</span>
<span class="c1">// in turn trigger the install event again.</span>
<span class="kr">const</span> <span class="nx">PRECACHE</span> <span class="o">=</span> <span class="s1">'precache-v1'</span><span class="p">;</span>
<span class="kr">const</span> <span class="nx">RUNTIME</span> <span class="o">=</span> <span class="s1">'runtime'</span><span class="p">;</span>
<span class="c1">// A list of local resources we always want to be cached.</span>
<span class="kr">const</span> <span class="nx">PRECACHE_URLS</span> <span class="o">=</span> <span class="p">[</span>
<span class="s1">'index.html'</span><span class="p">,</span>
<span class="s1">'./'</span><span class="p">,</span> <span class="c1">// Alias for index.html</span>
<span class="s1">'styles.css'</span><span class="p">,</span>
<span class="s1">'../../styles/main.css'</span><span class="p">,</span>
<span class="s1">'demo.js'</span>
<span class="p">];</span>
<span class="c1">// The install handler takes care of precaching the resources we always need.</span>
<span class="nx">self</span><span class="p">.</span><span class="nx">addEventListener</span><span class="p">(</span><span class="s1">'install'</span><span class="p">,</span> <span class="nx">event</span> <span class="o">=></span> <span class="p">{</span>
<span class="nx">event</span><span class="p">.</span><span class="nx">waitUntil</span><span class="p">(</span>
<span class="nx">caches</span><span class="p">.</span><span class="nx">open</span><span class="p">(</span><span class="nx">PRECACHE</span><span class="p">)</span>
<span class="p">.</span><span class="nx">then</span><span class="p">(</span><span class="nx">cache</span> <span class="o">=></span> <span class="nx">cache</span><span class="p">.</span><span class="nx">addAll</span><span class="p">(</span><span class="nx">PRECACHE_URLS</span><span class="p">))</span>
<span class="p">.</span><span class="nx">then</span><span class="p">(</span><span class="nx">self</span><span class="p">.</span><span class="nx">skipWaiting</span><span class="p">())</span>
<span class="p">);</span>
<span class="p">});</span>
<span class="c1">// The activate handler takes care of cleaning up old caches.</span>
<span class="nx">self</span><span class="p">.</span><span class="nx">addEventListener</span><span class="p">(</span><span class="s1">'activate'</span><span class="p">,</span> <span class="nx">event</span> <span class="o">=></span> <span class="p">{</span>
<span class="kr">const</span> <span class="nx">currentCaches</span> <span class="o">=</span> <span class="p">[</span><span class="nx">PRECACHE</span><span class="p">,</span> <span class="nx">RUNTIME</span><span class="p">];</span>
<span class="nx">event</span><span class="p">.</span><span class="nx">waitUntil</span><span class="p">(</span>
<span class="nx">caches</span><span class="p">.</span><span class="nx">keys</span><span class="p">().</span><span class="nx">then</span><span class="p">(</span><span class="nx">cacheNames</span> <span class="o">=></span> <span class="p">{</span>
<span class="k">return</span> <span class="nx">cacheNames</span><span class="p">.</span><span class="nx">filter</span><span class="p">(</span><span class="nx">cacheName</span> <span class="o">=></span> <span class="o">!</span><span class="nx">currentCaches</span><span class="p">.</span><span class="nx">includes</span><span class="p">(</span><span class="nx">cacheName</span><span class="p">));</span>
<span class="p">}).</span><span class="nx">then</span><span class="p">(</span><span class="nx">cachesToDelete</span> <span class="o">=></span> <span class="p">{</span>
<span class="k">return</span> <span class="nx">Promise</span><span class="p">.</span><span class="nx">all</span><span class="p">(</span><span class="nx">cachesToDelete</span><span class="p">.</span><span class="nx">map</span><span class="p">(</span><span class="nx">cacheToDelete</span> <span class="o">=></span> <span class="p">{</span>
<span class="k">return</span> <span class="nx">caches</span><span class="p">.</span><span class="k">delete</span><span class="p">(</span><span class="nx">cacheToDelete</span><span class="p">);</span>
<span class="p">}));</span>
<span class="p">}).</span><span class="nx">then</span><span class="p">(()</span> <span class="o">=></span> <span class="nx">self</span><span class="p">.</span><span class="nx">clients</span><span class="p">.</span><span class="nx">claim</span><span class="p">())</span>
<span class="p">);</span>
<span class="p">});</span>
<span class="c1">// The fetch handler serves responses for same-origin resources from a cache.</span>
<span class="c1">// If no response is found, it populates the runtime cache with the response</span>
<span class="c1">// from the network before returning it to the page.</span>
<span class="nx">self</span><span class="p">.</span><span class="nx">addEventListener</span><span class="p">(</span><span class="s1">'fetch'</span><span class="p">,</span> <span class="nx">event</span> <span class="o">=></span> <span class="p">{</span>
<span class="c1">// Skip cross-origin requests, like those for Google Analytics.</span>
<span class="k">if</span> <span class="p">(</span><span class="nx">event</span><span class="p">.</span><span class="nx">request</span><span class="p">.</span><span class="nx">url</span><span class="p">.</span><span class="nx">startsWith</span><span class="p">(</span><span class="nx">self</span><span class="p">.</span><span class="nx">location</span><span class="p">.</span><span class="nx">origin</span><span class="p">))</span> <span class="p">{</span>
<span class="nx">event</span><span class="p">.</span><span class="nx">respondWith</span><span class="p">(</span>
<span class="nx">caches</span><span class="p">.</span><span class="nx">match</span><span class="p">(</span><span class="nx">event</span><span class="p">.</span><span class="nx">request</span><span class="p">).</span><span class="nx">then</span><span class="p">(</span><span class="nx">cachedResponse</span> <span class="o">=></span> <span class="p">{</span>
<span class="k">if</span> <span class="p">(</span><span class="nx">cachedResponse</span><span class="p">)</span> <span class="p">{</span>
<span class="k">return</span> <span class="nx">cachedResponse</span><span class="p">;</span>
<span class="p">}</span>
<span class="k">return</span> <span class="nx">caches</span><span class="p">.</span><span class="nx">open</span><span class="p">(</span><span class="nx">RUNTIME</span><span class="p">).</span><span class="nx">then</span><span class="p">(</span><span class="nx">cache</span> <span class="o">=></span> <span class="p">{</span>
<span class="k">return</span> <span class="nx">fetch</span><span class="p">(</span><span class="nx">event</span><span class="p">.</span><span class="nx">request</span><span class="p">).</span><span class="nx">then</span><span class="p">(</span><span class="nx">response</span> <span class="o">=></span> <span class="p">{</span>
<span class="c1">// Put a copy of the response in the runtime cache.</span>
<span class="k">return</span> <span class="nx">cache</span><span class="p">.</span><span class="nx">put</span><span class="p">(</span><span class="nx">event</span><span class="p">.</span><span class="nx">request</span><span class="p">,</span> <span class="nx">response</span><span class="p">.</span><span class="nx">clone</span><span class="p">()).</span><span class="nx">then</span><span class="p">(()</span> <span class="o">=></span> <span class="p">{</span>
<span class="k">return</span> <span class="nx">response</span><span class="p">;</span>
<span class="p">});</span>
<span class="p">});</span>
<span class="p">});</span>
<span class="p">})</span>
<span class="p">);</span>
<span class="p">}</span>
<span class="p">});</span></code></pre></figure>
</body>
</html>