javascript - Is there a function, like componentWillUnmount, that will fire before the page is refreshed

Question

I want a function, to send a request to a server (don't care about response) before a user refreshes the page.

I've tried using the componentWillUnmount approach but the page refresh doesn't call this function. e.g.

import React, { useEffect } from 'react';

const ComponentExample => () => {
    useEffect(() => {
        return () => {
            // componentWillUnmount in functional component.
            // Anything in here is fired on component unmount.
            // Call my server to do some work
        }
    }, []) }

Does anyone have any ideas how to do this?

Answer 1

You could try listening for the window.beforeunload event.

The beforeunload event is fired when the window, the document and its resources are about to be unloaded. The document is still visible and the event is still cancelable at this point.

useEffect(() => {
  const unloadCallback = (event) => { ... };

  window.addEventListener("beforeunload", unloadCallback);
  return () => window.removeEventListener("beforeunload", unloadCallback);
}, []);

Note: This will respond to anything that causes the page to unload though.

Note 2:

However note that not all browsers support this method, and some instead require the event handler to implement one of two legacy methods:

• assigning a string to the event's returnValue property
• returning a string from the event handler.