[javascript] ie下audio不支持一些媒体类型

        <audio id="chatMessageAudio">
            <source id="chatMessageAudioSource"  />
        </audio>

            var b = document.getElementById("chatMessageAudio");
            if (b.canPlayType('audio/ogg; codecs="vorbis"')) {
                alert(1);
                b.type= 'audio/mpeg';
                b.src= '/static/images/alert2.ogg';
                var p = b.play();
                p && p.then(function () {
                }).catch(function (e) {
                });
            }