JsAudioChunk

// offset is optional, defaults to zero
var chunk = fb.GetAudioChunk(requested_length, offset);

if (chunk) {
    // chunk now has the following properties
    // chunk.ChannelConfig
    // chunk.ChannelCount
    // chunk.SampleRate
    // chunk.SampleCount
    // chunk.Data

    var data = chunk.Data

    var channel_count = chunk.ChannelCount;
    for (var i = 0; i < data.length; i += channel_count) {
        // assuming stereo
        var l = data[i];
        var r = data[i + 1];
    }
}