HTMLMediaElement: loadstart Ereignis

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.

Das loadstart Ereignis wird ausgelöst, wenn der Browser begonnen hat, eine Ressource zu laden.

Syntax

Verwenden Sie den Ereignisnamen in Methoden wie addEventListener(), oder setzen Sie eine Ereignis-Handler-Eigenschaft.

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

onloadstart = (event) => { }

Ereignistyp

Ein generisches Event.

Beispiele

Live-Beispiel

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);
  }
});

Ergebnis

Spezifikationen

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