The navigateerror event of the Navigation interface is fired when a navigation fails.

For example, if the network is down, any fetch() method invoked to handle a navigation will fail, and the error will be routed to navigateerror.

Use the event name in methods like addEventListener(), or set an event handler property.

addEventListener("navigateerror", (event) => {});

onnavigateerror = (event) => {};

An ErrorEvent. Inherits from Event.

You might deal with a successful navigation by hiding a previously displayed progress indicator, like this:

navigation.addEventListener("navigatesuccess", (event) => {
  loadingIndicator.hidden = true;
});

Or you might show an error message on failure:

navigation.addEventListener("navigateerror", (event) => {
  loadingIndicator.hidden = true; // also hide indicator
  showMessage(`Failed to load page: ${event.message}`);
});

• Modern client-side routing: the Navigation API
• Navigation API explainer
• Domenic Denicola's Navigation API live demo