index.html

<!DOCTYPE html>
<html>
<head>
<script>

function decode(arrayBuffer, audioContext, callback)
{
    if (window.Worker) {
        var w = new Worker("mp3worker.min.js");

        w.onmessage = function(e) {
            var data        = e.data;
            var channelData = data.channelData;
            var audioBuffer = null;

            if (channelData && data.sampleRate) {
                audioBuffer = audioContext.createBuffer(channelData.length, channelData[0].length, data.sampleRate);
                
                for (var i = 0; i < data.channelData.length; i++) {
                    audioBuffer.getChannelData(i).set(data.channelData[i]);
                }
            }

            callback(audioBuffer);
        };

        w.postMessage(arrayBuffer);

    } else {
        callback(null);
    }
}


function handleLoad()
{
    var context = window.webkitAudioContext ? new webkitAudioContext() : new AudioContext();

    var request = new XMLHttpRequest();
    request.responseType = "arraybuffer";
    request.open("GET", "sounds/test.mp3", true);

    request.addEventListener("load", function(e) {
        decode(request.response, context, function(audioBuffer) {
            console.log(audioBuffer);
            var source = context.createBufferSource();
            source.buffer = audioBuffer;
            source.connect(context.destination);
            source.start();
        });
    }, false);

    request.send(null);
}

</script>
</head>
<body onload="handleLoad()">

</body>
</html>