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

Browser compatibility

BCD tables only load in the browser

See also