�∫„Åó„Å∏„ÅÆÁõ¥Êé•„É™„É≥„ÇØ">#</a></h3><p>‚ñ∏ <strong>prependOnceListener</strong>(<code>event</code>, <code>listener</code>): <a href="/werift-webrtc/website/build/ja/docs/api/classes/mediastreamtrack">MediaStreamTrack</a></p><h4><a aria-hidden="true" tabindex="-1" class="anchor enhancedAnchor_2LWZ" id="parameters-10"></a>Parameters<a class="hash-link" href="#parameters-10" title="Ë¶ãÂá∫„Åó„Å∏„ÅÆÁõ¥Êé•„É™„É≥„ÇØ">#</a></h4><tab