HTML loadedmetadata DOM Event: Reference and Examples

When someone interacts with a webpage, the browser sends events to the relevant JavaScript code. The loadedmetadata event happens when basic media details such as dimensions or duration are available.

When loadedmetadata happens

Basic media details such as dimensions or duration are available.

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 loadedmetadata...</p>
<script>
    const eventTarget = document.getElementById("demo-target");
    const eventStatus = document.getElementById("event-status");

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

Reading the code

The browser listens for loadedmetadata 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 a media file and read its duration or videoWidth.

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 a media file and read its duration or videoWidth. Then change one thing in the example and observe whether the event still fires.

Common Beginner Mistakes

• Expecting loadedmetadata to fire without its required user action or browser condition.
• Load a media file and read its duration or videoWidth.
• Adding repeated event listeners without considering cleanup or unwanted side effects.

Key Takeaways

• loadedmetadata reports basic media details such as dimensions or duration are available.
• addEventListener("loadedmetadata", ...) listens for the event on the appropriate target.
• Load a media file and read its duration or videoWidth.