HTMLMediaElement: loadstart event

Baseline Widely available

This feature is well established and works across many devices and browser versions. It’s been available across browsers since ⁨July 2015⁩.

The loadstart event is fired when the browser has started to load a resource.

Syntax

Use the event name in methods like addEventListener(), or set an event handler property.

addEventListener("loadstart", (event) => { })
onloadstart = (event) => { }

Event type

A generic Event.

Examples

Live example

HTML

html

<div class="example">
 <button type="button">Load video</button>
 <video controls width="250"></video>
 <div class="event-log">
 <label for="eventLog">Event log:</label>
 <textarea readonly class="event-log-contents" id="eventLog"></textarea>
 </div>
</div>

.event-log-contents {
 width: 18rem;
 height: 5rem;
 border: 1px solid black;
 margin: 0.2rem;
 padding: 0.2rem;
}
.example {
 display: grid;
 grid-template-areas:
 "button log"
 "video log";
}
button {
 grid-area: button;
 width: 10rem;
 margin: 0.5rem 0;
}
video {
 grid-area: video;
}
.event-log {
 grid-area: log;
}
.event-log > label {
 display: block;
}

JavaScript

const loadVideo = document.querySelector("button");
const video = document.querySelector("video");
const eventLog = document.querySelector(".event-log-contents");
let source = null;
function handleEvent(event) {
 eventLog.textContent += `${event.type}\n`;
}
video.addEventListener("loadstart", handleEvent);
video.addEventListener("progress", handleEvent);
video.addEventListener("canplay", handleEvent);
video.addEventListener("canplaythrough", handleEvent);
loadVideo.addEventListener("click", () => {
 if (source) {
 document.location.reload();
 } else {
 loadVideo.textContent = "Reset example";
 source = document.createElement("source");
 source.setAttribute("src", "/shared-assets/videos/flower.webm");
 source.setAttribute("type", "video/webm");
 video.appendChild(source);
 }
});