---
title: AudioContext.createAnalyser()
slug: Web/API/BaseAudioContext/createAnalyser
translation_of: Web/API/BaseAudioContext/createAnalyser
original_slug: Web/API/AudioContext/createAnalyser
---
<p>{{ APIRef("Web Audio API") }}</p>

<div>
<p>{{ domxref("AudioContext") }}的<code>createAnalyser()</code>方法能创建一个{{ domxref("AnalyserNode") }}，可以用来获取音频时间和频率数据，以及实现数据可视化。</p>
</div>

<div class="note">
<p><strong>注意</strong>：关于该节点的更多信息，请查看{{domxref("AnalyserNode")}}</p>
</div>

<h2 id="语法">语法</h2>

<pre class="brush: js">var audioCtx = new AudioContext();
var analyser = audioCtx.createAnalyser();</pre>

<h3 id="Description" name="Description">返回值</h3>

<p>{{domxref("AnalyserNode")}}对象</p>

<h2 id="Examples" name="Examples">例子</h2>

<p>下面的例子展示了AudioContext创建分析器节点的基本用法，然后用requestAnimationFrame()来反复获取时域数据，并绘制出当前音频输入的“示波器风格”输出。更多完整例子请查看<a href="https://mdn.github.io/voice-change-o-matic/">Voice-change-O-matic</a> demo (中<a href="https://github.com/mdn/voice-change-o-matic/blob/gh-pages/scripts/app.js#L128-L205">app.js的128–205行</a>代码)</p>

<pre class="brush: js">var audioCtx = new (window.AudioContext || window.webkitAudioContext)();
var analyser = audioCtx.createAnalyser();

  ...

analyser.fftSize = 2048;
var bufferLength = analyser.fftSize;
var dataArray = new Uint8Array(bufferLength);
analyser.getByteTimeDomainData(dataArray);

// draw an oscilloscope of the current audio source

function draw() {

      drawVisual = requestAnimationFrame(draw);

      analyser.getByteTimeDomainData(dataArray);

      canvasCtx.fillStyle = 'rgb(200, 200, 200)';
      canvasCtx.fillRect(0, 0, WIDTH, HEIGHT);

      canvasCtx.lineWidth = 2;
      canvasCtx.strokeStyle = 'rgb(0, 0, 0)';

      canvasCtx.beginPath();

      var sliceWidth = WIDTH * 1.0 / bufferLength;
      var x = 0;

      for(var i = 0; i &lt; bufferLength; i++) {

        var v = dataArray[i] / 128.0;
        var y = v * HEIGHT/2;

        if(i === 0) {
          canvasCtx.moveTo(x, y);
        } else {
          canvasCtx.lineTo(x, y);
        }

        x += sliceWidth;
      }

      canvasCtx.lineTo(canvas.width, canvas.height/2);
      canvasCtx.stroke();
    };

    draw();</pre>

<h2 id="规范">规范</h2>

<table class="standard-table">
 <tbody>
  <tr>
   <th scope="col">Specification</th>
   <th scope="col">Status</th>
   <th scope="col">Comment</th>
  </tr>
  <tr>
   <td>{{SpecName('Web Audio API', '#widl-AudioContext-createAnalyser-AnalyserNode', 'createAnalyser()')}}</td>
   <td>{{Spec2('Web Audio API')}}</td>
   <td> </td>
  </tr>
 </tbody>
</table>

<h2 id="浏览器兼容性">浏览器兼容性</h2>

<div>{{CompatibilityTable}}</div>

<div id="compat-desktop">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Chrome</th>
   <th>Firefox (Gecko)</th>
   <th>Internet Explorer</th>
   <th>Opera</th>
   <th>Safari (WebKit)</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>{{CompatChrome(10.0)}}{{property_prefix("webkit")}}</td>
   <td>{{CompatGeckoDesktop(25.0)}} </td>
   <td>{{CompatNo}}</td>
   <td>15.0{{property_prefix("webkit")}}<br>
    22</td>
   <td>6.0{{property_prefix("webkit")}}</td>
  </tr>
 </tbody>
</table>
</div>

<div id="compat-mobile">
<table class="compat-table">
 <tbody>
  <tr>
   <th>Feature</th>
   <th>Android</th>
   <th>Firefox Mobile (Gecko)</th>
   <th>Firefox OS</th>
   <th>IE Mobile</th>
   <th>Opera Mobile</th>
   <th>Safari Mobile</th>
   <th>Chrome for Android</th>
  </tr>
  <tr>
   <td>Basic support</td>
   <td>{{CompatUnknown}}</td>
   <td>26.0</td>
   <td>1.2</td>
   <td>{{CompatUnknown}}</td>
   <td>{{CompatUnknown}}</td>
   <td>{{CompatUnknown}}</td>
   <td>33.0</td>
  </tr>
 </tbody>
</table>
</div>

<h2 id="另见">另见</h2>

<ul>
 <li><a href="/en-US/docs/Web_Audio_API/Using_Web_Audio_API">Using the Web Audio API</a></li>
</ul>