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---
title: 'HTMLMediaElement: loadstart イベント'
slug: Web/API/HTMLMediaElement/loadstart_event
tags:
- API
- Event
- HTMLMediaElement
- Reference
- Web
- loadstart
- イベント
translation_of: Web/API/HTMLMediaElement/loadstart_event
---
<div>{{APIRef}}</div>
<p><strong><code>loadstart</code></strong> イベントは、ブラウザーがリソースの読み込みを開始したときに発生します。</p>
<table class="properties">
<tbody>
<tr>
<th scope="row">バブリング</th>
<td>なし</td>
</tr>
<tr>
<th scope="row">キャンセル可能</th>
<td>いいえ</td>
</tr>
<tr>
<th scope="row">インターフェイス</th>
<td>{{domxref("Event")}}</td>
</tr>
<tr>
<th scope="row">イベントハンドラープロパティ</th>
<td>{{domxref("GlobalEventHandlers/onloadstart", "onloadstart")}}</td>
</tr>
</tbody>
</table>
<h2 id="Examples" name="Examples">例</h2>
<h3 id="Live_example" name="Live_example">ライブデモ</h3>
<h4 id="HTML">HTML</h4>
<pre class="brush: 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></pre>
<div class="hidden">
<h4 id="CSS">CSS</h4>
<pre class="brush: css">.event-log-contents {
width: 18rem;
height: 5rem;
border: 1px solid black;
margin: .2rem;
padding: .2rem;
}
.example {
display: grid;
grid-template-areas:
"button log"
"video log";
}
button {
grid-area: button;
width: 10rem;
margin: .5rem 0;
}
video {
grid-area: video;
}
.event-log {
grid-area: log;
}
.event-log>label {
display: block;
}
</pre>
</div>
<h4 id="JS">JS</h4>
<pre class="brush: 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);
}
});</pre>
<h4 id="Result" name="Result">結果</h4>
<p>{{ EmbedLiveSample('Live_example', '100%', '200px') }}</p>
<h2 id="Specifications" name="Specifications">仕様書</h2>
<table class="standard-table">
<thead>
<tr>
<th scope="col">仕様書</th>
<th scope="col">状態</th>
</tr>
</thead>
<tbody>
<tr>
<td>{{SpecName('HTML WHATWG', "media.html#event-media-loadstart", "loadstart media event")}}</td>
<td>{{Spec2('HTML WHATWG')}}</td>
</tr>
<tr>
<td>{{SpecName('HTML5 W3C', "embedded-content-0.html#event-media-loadstart", "loadstart media event")}}</td>
<td>{{Spec2('HTML5 W3C')}}</td>
</tr>
</tbody>
</table>
<h2 id="Browser_compatibility" name="Browser_compatibility">ブラウザーの対応</h2>
<p>{{Compat("api.HTMLMediaElement.loadstart_event")}}</p>
<h2 id="See_also" name="See_also">関連情報</h2>
<ul>
<li>{{domxref("HTMLAudioElement")}}</li>
<li>{{domxref("HTMLVideoElement")}}</li>
<li>{{HTMLElement("audio")}}</li>
<li>{{HTMLElement("video")}}</li>
</ul>
|
