provide several useful functions for handling Web Audio API

webAudioUtils.js

// check if support Web Audio
var supportWebAudio = (function(){
    // check <audio> tag first
    var ele = document.createElement('audio');
    if (!ele) {
        return false;
    }

    // check Web Audio's context
    try {
        var ctx = new (window.AudioContext || window.webkitAudioContext || window.mozAudioContext)();
        return ctx ? true : false;
    } catch (e) {
        return false;
    }
})();