HTML progress DOM Event: Reference and Examples

When someone interacts with a webpage, the browser sends events to the relevant JavaScript code. The progress event happens when loading or media progress is reported.

When progress happens

Loading or media progress is reported.

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

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

Reading the code

The browser listens for progress 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 sufficiently large media resource; progress events are not guaranteed at fixed intervals.

Do not expect regular timing; when available, eventDetails.loaded and total describe transfer progress.

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 sufficiently large media resource; progress events are not guaranteed at fixed intervals. Then change one thing in the example and observe whether the event still fires.

Common Beginner Mistakes

• Expecting progress to fire without its required user action or browser condition.
• Load a sufficiently large media resource; progress events are not guaranteed at fixed intervals.
• Adding repeated event listeners without considering cleanup or unwanted side effects.

Key Takeaways

• progress reports loading or media progress is reported.
• addEventListener("progress", ...) listens for the event on the appropriate target.
• Load a sufficiently large media resource; progress events are not guaranteed at fixed intervals.