Online and offline event detection can be implemented in the renderer process using standard HTML5 APIs, as shown in the following example.
main.js
const {app, BrowserWindow} = require('electron')
let onlineStatusWindow
app.on('ready', () => {
onlineStatusWindow = new BrowserWindow({ width: 0, height: 0, show: false })
onlineStatusWindow.loadURL(`file://${__dirname}/online-status.html`)
})
online-status.html
<!DOCTYPE html>
<html>
<body>
<script>
const alertOnlineStatus = () => {
window.alert(navigator.onLine ? 'online' : 'offline')
}
window.addEventListener('online', alertOnlineStatus)
window.addEventListener('offline', alertOnlineStatus)
alertOnlineStatus()
</script>
</body>
</html>
There may be instances where you want to respond to these events in the main process as well. The main process however does not have a navigator
object and thus cannot detect these events directly. Using Electron’s inter-process communication utilities, the events can be forwarded to the main process and handled as needed, as shown in the following example.
main.js
const {app, BrowserWindow, ipcMain} = require('electron')
let onlineStatusWindow
app.on('ready', () => {
onlineStatusWindow = new BrowserWindow({ width: 0, height: 0, show: false })
onlineStatusWindow.loadURL(`file://${__dirname}/online-status.html`)
})
ipcMain.on('online-status-changed', (event, status) => {
console.log(status)
})
online-status.html
<!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>
NOTE: If Electron is not able to connect to a local area network (LAN) or a router, it is considered offline; all other conditions return true
. So while you can assume that Electron is offline when navigator.onLine
returns a false
value, you cannot assume that a true
value necessarily means that Electron can access the internet. You could be getting false positives, such as in cases where the computer is running a virtualization software that has virtual ethernet adapters that are always “connected.” Therefore, if you really want to determine the internet access status of Electron, you should develop additional means for checking.