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.

loadstart 事件当浏览器开始载入一个资源文件时 fired.

Bubbles No
可撤销 No
Interface Event
Event handler property onloadstart

Examples

Live example

HTML

html
<div class="example">
  <button type="button">Load video</button>
  <video controls width="250"></video>

  <div class="event-log">
    <label>Event log:</label>
    <textarea readonly class="event-log-contents"></textarea>
  </div>
</div>

JS

js
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 = 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",
      "https://interactive-examples.mdn.mozilla.net/media/examples/flower.webm",
    );
    source.setAttribute("type", "video/webm");

    video.appendChild(source);
  }
});

Result

Specifications

Specification
HTML
# event-media-loadstart
HTML
# handler-onloadstart

Browser compatibility

Report problems with this compatibility data on GitHub
desktopmobile
Chrome
Edge
Firefox
Opera
Safari
Chrome Android
Firefox for Android
Opera Android
Safari on iOS
Samsung Internet
WebView Android
WebView on iOS
loadstart event

Legend

Tip: you can click/tap on a cell for more information.

Full support
Full support

See also