Hello everyone ๐
In this article, we are going to learn how can we detect the internet connection state on our website.
This can be very useful to improve user experience by showing snack messages or pop-ups when the browser is not able to connect to the internet.
Implementation
We can get the current state of the connection by using window.navigator.onLine
, which will return a boolean
value.
-
true
if connected. -
false
if not connected.
const online = window.navigator.onLine;
if (online) {
// Is connected to internet
} else {
// Not connected to internet
}
If the browser doesn't support
window.navigator.onLine
the above example will always come out asfalse
orundefined
.
Connection State Changes Listener
We can also detect the connection state by listening for network state change events i.e, online
and offline
.
window.addEventListener('offline', function(e) {
// Network disconnected
}
);
window.addEventListener('online', function(e) {
// Network connected
}
);
It's very easy to implement but there are some side cases where it might give a false-positive result.
The computer is connected to a mobile hotspot, but mobile internet is not working then also you can get an
online
status.The computer is running a virtualization software that has virtual ethernet adapters that are always "connected".
Originally published on blog.bibekkakati.me
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Top comments (4)
I like the simplicity and the fact you list the edge cases that may cause inaccuracy.
I wonder what the consensus is on polling a same-host endpoint as a ping (by updating the response with the current timestamp) to check the connection can at least reach the remote destination
With WebSocket, this becomes slightly less important due to the connect and disconnect events firing as expected so long as reconnect is configured.
Polling is a good way, but to use it as an alternative to the listeners we will have to poll very frequently.
I prefer to use the listeners as those side cases are not so impacting. After a false-positive result, if we send a valid request and it fails, we will get to know about the false-positive status. At last, it depends on the application and it's working.
Simple feature and nicely explained. Such minute things makes the day! Thanks for writing this.
Thank you @Ashish.