【问题标题】：How can i create a promise for the end of playing sound?我怎样才能为结束播放声音创建一个承诺？
【发布时间】：2015-07-16 04:35:47
【问题描述】：

我有一个加载声音的简单 JavaScript：

  prefix = 'modules/sounds/';
 _sounds = ['nameOfSound','nameOfSound','nameOfSound'];


 for (var sound in _sounds) {
                if (_sounds.hasOwnProperty(sound)) {
                    var cached = _sounds[sound];
                    cached.audio = new Audio(prefix + cached.src);
                    }
                }
            }

所有都被缓存在这里，然后在角度我只有一个执行以下功能的服务：

 this.play = function(trackName) {
        _sounds[trackName].audio.play();
    };

我想要的是对声音的简单承诺，所以当我调用它时，我会有这样的东西：

soundService.play('boom').then(function(){
    do something here
});

这可能吗？

【问题讨论】：

你有一个简单的回调解决方案吗？声音结束有什么事件吗？
那我为什么要问，我怎么能在声音结束时有回调？

标签： javascript angularjs html5-audio

【解决方案1】：

您可以创建一个可以实现以适应您的设置的通用对象：

function play(url) {
     return new Promise(function(resolve, reject) {   // return a promise
         var audio = new Audio();                     // create audio wo/ src
         audio.preload = "auto";                      // intend to play through
         audio.autoplay = true;                       // autoplay when loaded
         audio.onerror = reject;                      // on error, reject
         audio.onended = resolve;                     // when done, resolve

         audio.src = path + url + suffix; // just for example
     });
}

现在你可以打电话了：

play("boom").then(function() {

});

由于它们的缓冲行为，缓存音频元素没有什么意义。指示预加载将告诉浏览器您将要播放音频文件。在我看来，这对客户和系统也更好。

示例

function play(url) {
  return new Promise(function(resolve, reject) { // return a promise
    var audio = new Audio();                     // create audio wo/ src
    audio.preload = "auto";                      // intend to play through
    audio.autoplay = true;                       // autoplay when loaded
    audio.onerror = reject;                      // on error, reject
    audio.onended = resolve;                     // when done, resolve

    audio.src = url
  });
}

play(sample).then(function() {
  alert("Done!");
})

<script>
var sample = "data:audio/wav;base64,UklGRiAOAABXQVZFZm10IBAAAAABAAEA71YAAO9WAAABAAgAZGF0YfsNAACCgoKAgYKCgoKCgoGCgoGBgIB/foCAf35+fn19fX1+foCCgYGAgICAfn5+fnx8fn5/f3+AgICBgYKCg4OCgIB/fn5+gIB/gIGBgoGAf4CAgYB+fn5+fXx8fHx9fn59fX1+foB/f39+gIGAgIGBgIB+f4CAgICAgH+AgoKBgIGCgoKChYWBfHp5eHh5enx/goSGiYqMi4mHhoaEhIOCgH58fHx8fHx+fn5/gICAgYGCgoKDhIODgoCBgYCAgICAf319fn59fn5+fn+Afn6AgYCBgYCAf36AgICAgH5+f4CAgIB+fn59fHx+fn5/gYGBgoOEgoGBgYB+fn59f35+gIB+fn+AgICBgICAfn+AgICCgYCBgYGCgoKCgICBgH+AgICAgIGCgoGAgX9/foCAgICAgIB/gICAgYB+gIGCgoKCgICAf4CCg4KBgYCAfn6AgH99e3x9fXx8fH5/f4CAgICAgIGCgoOEgoKCg4OCgoKCgICAgICAgYKCgoKCgYCBgYKCgoKCgoCAgYF+fn5/gICAgH59foCAgX9+gIB+fX19fn+AgH5/f3+Afn19fX5/gICAf4CAgH59fX6AgH5+gICAf4CAgICAgYKBgoGAfn6AgICAgIKCgICAgICAf35+fn59fX1+fn6AgH9+gIGAf4CAgYCAgICBgYB/fn+Bg4F/foGDgn59gISEgn5+g4aFgX+AhIWEfnyBhoSAfH2Cg396en6Eg357foSGgXx9hIeEfnuAhoZ+en6FhoF7fYSIhH16foSCenl+g4R/eXuChX55eoCCfHd5foJ+enp+hIF6e4KEgXt7goWBe3yChoJ7fISGgXp8g4WAfH6Eh4F6fYSGgHp9hIaAe3+GhoB7gIeGfnyChoN8e4KGg3x6gYaBenyEhn95fISGfnp+h4Z8eH+Ggnl6goiAd3iEiIB4fImKgHh+h4R5cnmGhXdzfoiDd3aAioR4eYaMgnV3hoyCdXmJjoJ2fIqMfnR6jI5/c3uMjn50fo6PfnJ7jY18cnuMjnpteY6Oem14jI56bXmOjnprdo6Se2h0jZJ7Z3GOl4BmbIqZgmZqip2HZGeKn4plZIaklGlggqKWalp4nppxWXKdontZaZOkhFxhi6eTZlyApp5yWHGeq4RYXoqolGNVd6Gfc1ZrmauKXFuHrJtnU3Siq35TX5Cxll5Sfq6rck5ooLaNVliOuaNkTXKnsH1MW5K2m11JdKqxfkxalLiaWkh0rrV5RFaYwJ1VQXe3t3ZDW52+llFGfrq2ckBbnsGWUEaAtq9uQl6evJBORn60sXREXJy+l1NCdrO0dD9VmL6eWD5wsbl8QFGUvaJeQ26tvIRIU5C6pGNEaqa5jVBOhLWvckZfnLuZWkh1rLSCTlWKs6hxTmSXsZReTnKirINUVoSsqHhSYJGwmmhTb5uqjmFWeKKog1hZgKSieVZgiaWacllqkKiacVttk6eWcF1xlKSTcWBykqKRbV5xkqKSbVprkKWWbFRok6yYalFqmbCVYExtnrCQXE9wnrCTYlNznaqPY1Z0mqaOZFZylqKMZlpykp6MbmN0jZeMdWdziJKNem5zhI6LfXN2goqHfXZ3gIeEfnt7foCBgYF+fn1+goSDfXp8goeHfnd4gIiKgnZ1fomKgXZ2foeJgnd0e4SJhn54eoKKjYV4dX6KkYt6cXiGkIx7bXOGkpGAcHKElJOCb26Aj5GGdG55iY+KfXJ0g46QhHNteY2Uindsc4aSjHxvcICOj4FycXuIjId8dHN7iIyGe3N1go+OgXVweImPhnlwdIGLh313dHiEiYR9eHZ7hIeGgnlyeYmPh3tvcIGRjYBybXqMkYZ6cXOBjY6Ee3R2hJCPhndud4yWj31ra3+Wl4RvaXaNmIp3b3SBjo6Cd3V4gYmJhH53dHyKj4p+cG+AlJaFcmt1ipSKdWpteoqMgHVzeICIioJ8e3h8h46KgHd0fpCVjHxxcYGTk4Z4cXaGkIuAeHJ0gY+QhnZrboOXloNvZ3SMmpB6amp6kJaIdm5xe4qOh310bnWHk5CAbmZzjpqQeGZmepWciW5lbYGVmId1bnF+jZKIem5qdYyZkHtoZHWRoZV4Y2J3lqORcmFlfpyjjnJla4CYnYpyZ2p8k5uLc2hse5GajnpsaXaLmpJ4aGp4kJuQeWtreIyak35uaXGGmJeEbmhziZ2dhWxpc4ibm4VuaHSImZqGcGpyg5KWiHNtdH6Jkox7bm93hpOSfm5wfIaNjH91eoGAgYeJg317eXqFi4R7eHh5gYiHgX54cneFi4d+dG90go+Nf3Z0doCLioJ/fXd2fYeMi4FzbHSGlJKDcmhwhZWXiXRqbH6Tl4t7cGtyhpaXi3hoan6Wn5N4ZGN0jJqTfGllcIGTmot1bG96i5eSfnBveIWPkIV4dnuBg4aHhYF+enR3goyLgHJrcYSUkoJzc3uEiomCfX6Af32AiIyIgnp1eIKKjYh+dHJ4hpGRhHZvdYaQjoJ3dnyCgn6AgoODfnh3foSHhoB5dHR9h4uHfXRyd4GMj4R0bnaDjIp+eHqAhIWAenuAg4WEfnd1fIWLioB1cnqEi4yFenZ4foOFgn99fHt8foCBgoKCgXx5fIKEhYJ7d3p+goOCgH5+foCCgYCAgIOAfnx8gIOEhoN/foGFhoN9e36DhoR+en2ChYSAfX2Ag4KBgYKDgoB+gIKCgoGAgYKAfn6ChYR9en2ChoeBenuAhYSAfX6Ag4SAfX2AgoKCgH9+fX2Ag4KBfXp7goaDgH19gIKBfoCBgHt6fIGDgn58fYGCgH59gIKBfXt+gYKCfXl6foKEgXx5e4KGhoF8e4CEhIKAfXt+gYGChISBfXx+hIeFfnp8gYaHhYB9gIKDg4KBgYB+foCEhIB8enyEiod+eHqBiIiCenh+g4SBfnx8fXx7fICAfXp7foSGgXx8foKEgn59foGCgoGBgYKAgICBgoSEgn5+goeKhHx4eYCHiIN7eHqCiod+eHl9goWFgHt7fYCEhYJ7dniAhoWAenh6goeEfnt6fIKGhH15en2DhoJ9e3x+gYOCgH59fICCgYKAfHx9goSCgX17foKEgn56fICCgHx8fX6AgYB+fn5+fn6AgoJ+e3yAg4WEgH5+gYOCgH5+gH9+fn6ChIB6eHuAhoZ+eXp/hIeEfn2Ag4KAgYWGhIGAf4KFhoOBfnx+goSFhIB+fYCEhoSCgH6AgoSDgoCAgIGCg4OBfn1+gYKAfnt8foGBgH98fH+CgoB8enyAgoKAfXt+g4OBfnyAgoJ+fHyAg4N+ent+goOCf319fn+ChIF9e3x/gIGAgIB+fX2AgoWFgHp7foKDgn59fYGDhIOCgYKFhIKCgYCBg4OCgH2AhIaEgHx7foKEhH56e36ChISAfHyAg4WDgoKAfoCCgX99e3h5fICAfnt8f4KBgH9+gYSEgH5/goSFhoJ9fH+DhoV/enp+hIiHg318foGDhIJ/fX2AhoiFf3p4fIOGg3p0dn+GhoB5dnmAhIOAfn59foGEhIJ+fHx8gISFgn57fH6DhIJ+fHx/goSEgH19fYCBgICAgICAfHx+goSCfnx8foGDhIF+fH6BgoSCfnx8gISEgX58fH+CgoB+fH5/f4CAgIB/fH2AgoOAfXx+gIKCgH19foCDhYOAfn6Bg4SDgH5+gYOFgn59foGCg4OAfn5/goKCg4GAgIGChIJ/fH2Ag4WEgHp6foKGhHx4eX2DhIN/enp+goODgH18gIKBgYGAfn59foGBgH59fX5+foCCgn58fX6Bg4F9fH5+fn6CgoB+foCDhIF+foCCgoF+fn+BgoKAf4CBgYB/gIB/gIODhIKAfoCChISBfn1+gYODgn9+foCCgoB+fH5/gIB+fHyAgoOCfn1/gYOEgn5+gIGBgYGAfHx8fYCAfn18fICCgoF/foCBgoJ/fH2BhYaEgX9+gYWGg357fICEhoSBfn2AhIWFgn58fYCDhIF+fn6ChIOAf39+gYSCgH59foGCgH58fn+BgX98fICAgYB+fn5+f39+fn5+fX5+fn1+fn5/gH58fYB/fn18foGDgoCAgYKDg4B+fX2AgYCAgH9+foCBf4CBgICAgICBgICBgX9+fn+AgYGAfn2AgYKBf35+gIOCgYGAgoKCgoF+gYKCgoSAgYGBgoKDgYB+foB/f35/gICBgYCBgYGBgYGCgoKAgICChISCgH6AgoKCgH5/gIGBgYCBgH5/gYKAfn6AgIGAfX1/gYODgH18fICCgn58fHx9foCAfn18foB+foB+fn6AgH5/fn6AgoGAfoCAgIB+fn1+gIGBgH19foKEgn99foCChISDgH6AgYGCgX5+gICAgYF+fX1+gICCgoGAgIKDg4KDgoKDhISBf4CBg4WEgn5+gIKDg4B9fHt8fn6Afnt7foGCgoB+fYCCgoKCgIGBgoGBgIKCgoKCgoKCgYCCg4OEg4F/foCCgYGAgICBgYF+fn19fX1+fX19fYCCgoGBgH5+fn5/fn18foGBgH17e36Cg4F+fH6Ag4KAfX1/gYKCgYCAf4CAgICBgH9+f4CAgoKAfn6BgoKBgICAgIGAfn19fn19fHx9f4B+f39+fn6AgH59fXx9gIB+fn9/gICBgoKCgoGBgYKCgoKBgICAgYGBgICAgICBgYCBgoKBgICAgoKCgoGBgYKCgYGCg4KBgICAgYCBgoGAgIGCgoGAgICBg4KAgICBgoKCgH5+foCAgH5+foCCgYCAgH9/gYGAf358fH6Afn18foAA"
</script>

【讨论】：

【解决方案2】：

您可以使用$q.defer() 编写服务。

app.service('service', ['$q', function($q){
    this.play = function play(sound) {
        var deferred = $q.defer();
        sound.play();
        sound.onended = function(e) {
          deferred.resolve(e);
        }
        return deferred.promise;
    }
}]);

您可以只调用服务并期待承诺返回。 service.play(sound).then(function(e){});

完整的 plunker 示例 - http://plnkr.co/edit/FJYjj4ehslqZQZmYyL1I?p=preview

【讨论】：

【解决方案3】：

当音频播放完毕时会发出一个“结束”事件。 Source

 this.play = function(trackName) {
    return new Promise(function(resolve, reject) {
        var audio = _sounds[trackName].audio;
        audio.addEventListener('ended', resolve);
        audio.play();
    });
 };

【讨论】：

等等，Audio 实例有 on 方法吗？
Brainfart 时刻。修好了。