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Here you can Sed posuere consectetur est at lobortis. Donec ullamcorper nulla non metus auctor fringilla. Maecenas sed diam eget risus varius blandit sit amet non magna. Donec id elit non mi porta gravida at eget metus. Praesent commodo cursus magna, vel scelerisque nisl consectetur et.

            
              html, body {
    width: 100%;
    height: 100%;
    margin: 0;
}
            
          
!
            
              'use strict';

var ctx, osc, gain, tapStart, startOnce, switchGain;

window.AudioContext = window.AudioContext || window.webkitAudioContext;
ctx = new AudioContext();
osc = ctx.createOscillator();
osc.type = 'sawtooth';
osc.frequency.value = 880;
gain = ctx.createGain();
// 初期値を1に設定
gain.gain.value = 1;
// OscillatorNode -> GainNode
osc.connect(gain);
// GainNode -> ctx.destination
gain.connect(ctx.destination);
// PCかSPかを判定して登録するイベント名を分岐
if (typeof window.ontouchstart !== 'undefined') {
    tapStart = 'touchstart';
} else {
    tapStart = 'mousedown';
}
// SPではユーザーが発生させたイベントでしか再生を開始できないため
// 初回の押下イベントで再生を開始する
startOnce = function() {
    // 再生開始
    osc.start(0);
    // 二回目以降は再生開始処理を実行しない  
    document.body.removeEventListener(tapStart, startOnce);
    document.body.addEventListener(tapStart, switchGain);
};
// 再生・停止(音量1・音量0)を切り替え
switchGain = function() {
    gain.gain.value = !gain.gain.value ? 1 : 0;
};
document.body.addEventListener(tapStart, startOnce);
            
          
!
999px
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