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Add tutorial on online/offline event detection

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Brent Ertz 2014-11-05 07:47:38 -07:00
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docs/README.md
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* [Debugging browser process](tutorial/debugging-browser-process.md)
* [Using Selenium and WebDriver](tutorial/using-selenium-and-webdriver.md)
* [DevTools extension](tutorial/devtools-extension.md)
* [Online/offline event detection](tutorial/online-offline-events.md)
## API references

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# Online/Offline Event Detection
Online and offline event detection can be implemented in the renderer process
using standard HTML5 APIs, as shown in the following example.
_main.js_
```javascript
var app = require('app');
var BrowserWindow = require('browser-window');
var onlineStatusWindow;
app.on('ready', function() {
onlineStatusWindow = new BrowserWindow({ width: 0, height: 0, show: false });
onlineStatusWindow.loadUrl('file://' + path.join(__dirname, '/online-status.html'));
});
```
_online-status.html_
```html
<html>
<body>
<script>
var alertOnlineStatus = function() {
window.alert(navigator.onLine ? 'online' : 'offline');
};
window.addEventListener('online', alertOnlineStatus);
window.addEventListener('offline', alertOnlineStatus);
alertOnlineStatus();
</script>
</body>
</html>
```
There may be instances where one wants to respond to these events in the
browser process as well. The browser process however does not have a
"navigator" object and thus cannot detect these events directly. Using
Atom-shell's inter-process communication utilities, the events can be forwarded
to the browser process and handled as needed, as shown in the following example.
_main.js_
```javascript
var app = require('app');
var ipc = require('ipc');
var BrowserWindow = require('browser-window');
var onlineStatusWindow;
app.on('ready', function() {
onlineStatusWindow = new BrowserWindow({ width: 0, height: 0, show: false });
onlineStatusWindow.loadUrl('file://' + path.join(__dirname, '/online-status.html'));
});
ipc.on('onlineStatusMessage', function(event, status) {
console.log(status);
});
```
_online-status.html_
```html
<html>
<body>
<script>
var ipc = require('ipc');
var updateOnlineStatus = function() {
ipc.send('onlineStatusMessage', navigator.onLine ? 'online' : 'offline');
};
window.addEventListener('online', updateOnlineStatus);
window.addEventListener('offline', updateOnlineStatus);
updateOnlineStatus();
</script>
</body>
</html>
```