---
title: RTCPeerConnection.canTrickleIceCandidates
slug: Web/API/RTCPeerConnection/canTrickleIceCandidates
tags:
  - API
  - ICE
  - Media
  - Property
  - RTCPeerConnection
  - Reference
  - Trickle
  - Trickling
  - WebRTC
  - WebRTC API
  - canTrickleIceCandidates
translation_of: Web/API/RTCPeerConnection/canTrickleIceCandidates
---
<div>{{APIRef("WebRTC")}}</div>

<p><span class="seoSummary">読み取り専用の <strong>{{domxref("RTCPeerConnection")}}</strong> プロパティ <code><strong>canTrickleIceCandidates</strong></code> は、リモート・ピアが <a href="https://tools.ietf.org/html/draft-ietf-mmusic-trickle-ice">trickled ICE 候補</a>を受け入れることができるかどうかを示す {{jsxref("Boolean")}} を返します。</span></p>

<p><strong>ICE トリックリング</strong>とは、最初のオファーや回答がすでに相手に送られた後も、候補者を送り続けるプロセスのことです。</p>

<p>This property is only set after having called {{domxref("RTCPeerConnection.setRemoteDescription()")}}.  Ideally, your signaling protocol provides a way to detect trickling support, so that you don't need to rely on this property. A WebRTC browser will always support trickle ICE. If trickling isn't supported, or you aren't able to tell, you can check for a falsy value for this property and then wait until the value of {{domxref("RTCPeerConnection.iceGatheringState", "iceGatheringState")}} changes to <code>"completed"</code> before creating and sending the initial offer. That way, the offer contains all of the candidates.</p>

<h2 id="Syntax">Syntax</h2>

<pre class="syntaxbox"> var <em>canTrickle</em> = <em>RTCPeerConnection</em>.canTrickleIceCandidates;</pre>

<h3 id="Value">Value</h3>

<p>A {{jsxref("Boolean")}} that is <code>true</code> if the remote peer can accept trickled ICE candidates and <code>false</code> if it cannot. If no remote peer has been established, this value is <code>null</code>.</p>

<div class="note">
<p><strong>Note:</strong> This property's value is determined once the local peer has called {{domxref("RTCPeerConnection.setRemoteDescription()")}}; the provided description is used by the ICE agent to determine whether or not the remote peer supports trickled ICE candidates.</p>
</div>

<h2 id="Example">Example</h2>

<pre class="brush: js">var pc = new RTCPeerConnection();
// The following code might be used to handle an offer from a peer when
// it isn't known whether it supports trickle ICE.
pc.setRemoteDescription(remoteOffer)
  .then(_ =&gt; pc.createAnswer())
  .then(answer =&gt; pc.setLocalDescription(answer))
  .then(_ =&gt;
    if (pc.canTrickleIceCandidates) {
      return pc.localDescription;
    }
    return new Promise(r =&gt; {
      pc.addEventListener('icegatheringstatechange', e =&gt; {
        if (e.target.iceGatheringState === 'complete') {
          r(pc.localDescription);
        }
      });
    });
  })
  .then(answer =&gt; sendAnswerToPeer(answer)) // signaling message
  .catch(e =&gt; handleError(e));

pc.addEventListener('icecandidate', e =&gt; {
  if (pc.canTrickleIceCandidates) {
    sendCandidateToPeer(e.candidate); // signaling message
  }
});
</pre>

<h2 id="Specifications">Specifications</h2>

<table class="standard-table">
 <thead>
  <tr>
   <th scope="col">Specification</th>
   <th scope="col">Status</th>
   <th scope="col">Comment</th>
  </tr>
 </thead>
 <tbody>
  <tr>
   <td>{{ SpecName('WebRTC 1.0', '#dom-rtcpeerconnection-cantrickleicecandidates', 'RTCPeerConnection.canTrickleIceCandidates') }}</td>
   <td>{{ Spec2('WebRTC 1.0') }}</td>
   <td>Initial specification.</td>
  </tr>
 </tbody>
</table>

<h2 id="Browser_compatibility">Browser compatibility</h2>



<p>{{Compat("api.RTCPeerConnection.canTrickleIceCandidates")}}</p>

<h2 id="See_also">See also</h2>

<ul>
 <li><a href="/en-US/docs/Web/Guide/API/WebRTC">WebRTC</a></li>
 <li>{{domxref("RTCPeerConnection.addIceCandidate()")}}</li>
 <li><a href="/en-US/docs/Web/API/WebRTC_API/Session_lifetime">Lifetime of a WebRTC session</a></li>
</ul>