HTML durationchange DOM Event: Reference and Examples

When someone interacts with a webpage, the browser sends events to the relevant JavaScript code. The durationchange event happens when the known total duration of a media file changes.

When durationchange happens

The known total duration of a media file changes.

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

<video id="demo-target" controls preload="metadata" width="320">
    <source src="sample-video.mp4" type="video/mp4">
</video>
<p id="event-status" role="status">Waiting for durationchange...</p>
<script>
    const eventTarget = document.getElementById("demo-target");
    const eventStatus = document.getElementById("event-status");

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

Reading the code

The browser listens for durationchange 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.

Load an audio or video file and inspect duration after metadata becomes available.

To test this example, put a real supported media file at the shown path. Events tied to buffering or download behavior may not fire in the same order on every connection. An unavailable sample file is not proof that your event listener is broken.

Try it in your browser

Open the page, show the Console panel, and follow this test: Load an audio or video file and inspect duration after metadata becomes available. Then change one thing in the example and observe whether the event still fires.

Common Beginner Mistakes

• Expecting durationchange to fire without its required user action or browser condition.
• Load an audio or video file and inspect duration after metadata becomes available.
• Adding repeated event listeners without considering cleanup or unwanted side effects.

Key Takeaways

• durationchange reports the known total duration of a media file changes.
• addEventListener("durationchange", ...) listens for the event on the appropriate target.
• Load an audio or video file and inspect duration after metadata becomes available.