HTML unload DOM Event: Reference and Examples

When someone interacts with a webpage, the browser sends events to the relevant JavaScript code. The unload event happens when a document is being unloaded.

When unload happens

A document is being unloaded.

You can listen for it using addEventListener(). That keeps event handling separate from HTML attributes such as onclick and works well with modern code organization.

A small working example

<p>Try navigation, but do not rely on unload: many modern browsers omit it.</p>
<p id="event-status" role="status">Waiting for unload...</p>
<script>
    const eventTarget = window;
    const eventStatus = document.getElementById("event-status");

    if (eventTarget) {
        eventTarget.addEventListener("unload", (eventDetails) => {
            eventStatus.textContent = "unload event received";
            console.log(eventDetails.type, eventDetails.target);
        });
    }
</script>

Reading the code

The browser listens for unload on the relevant target. When the event occurs, the callback receives eventDetails, updates the status message and logs the event name and target in Developer Tools.

This legacy event is unreliable and discouraged; use visibilitychange or pagehide when appropriate.

Some events need a specific browser condition, another tab or window, or a Web Component to reproduce. Read the trigger steps carefully before deciding that an event handler is not working.

Try it in your browser

Open the page, show the Console panel, and follow this test: This legacy event is unreliable and discouraged; use visibilitychange or pagehide when appropriate. Then change one thing in the example and observe whether the event still fires.

Common Beginner Mistakes

• Expecting unload to fire without its required user action or browser condition.
• This legacy event is unreliable and discouraged; use visibilitychange or pagehide when appropriate.
• Adding repeated event listeners without considering cleanup or unwanted side effects.

Key Takeaways

• unload reports a document is being unloaded.
• addEventListener("unload", ...) listens for the event on the appropriate target.
• This legacy event is unreliable and discouraged; use visibilitychange or pagehide when appropriate.