# 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
const {app, BrowserWindow} = require('electron')
let onlineStatusWindow
app.on('ready', () => {
onlineStatusWindow = new BrowserWindow({ width: 0, height: 0, show: false })
onlineStatusWindow.loadURL(`file://${__dirname}/online-status.html`)
})
```
_online-status.html_
```html
<!DOCTYPE html>
<html>
<body>
<script>
const alertOnlineStatus = () => {
window.alert(navigator.onLine ? 'online' : 'offline')
}
window.addEventListener('online', alertOnlineStatus)
window.addEventListener('offline', alertOnlineStatus)
alertOnlineStatus()
</script>
</body>
</html>
```
There may be instances where you want to respond to these events in the
main process as well. The main process however does not have a
`navigator` object and thus cannot detect these events directly. Using
Electron's inter-process communication utilities, the events can be forwarded
to the main process and handled as needed, as shown in the following example.
_main.js_
```javascript
const {app, BrowserWindow, ipcMain} = require('electron')
let onlineStatusWindow
app.on('ready', () => {
onlineStatusWindow = new BrowserWindow({ width: 0, height: 0, show: false })
onlineStatusWindow.loadURL(`file://${__dirname}/online-status.html`)
})
ipcMain.on('online-status-changed', (event, status) => {
console.log(status)
})
```
_online-status.html_
```html
<!DOCTYPE html>
<html>
<body>
<script>
const {ipcRenderer} = require('electron')
const updateOnlineStatus = () => {
ipcRenderer.send('online-status-changed', navigator.onLine ? 'online' : 'offline')
}
window.addEventListener('online', updateOnlineStatus)
window.addEventListener('offline', updateOnlineStatus)
updateOnlineStatus()
</script>
</body>
</html>
```