Check if AudioContext is supported and instance it

audioContext.js

var isAudioContextSupported = function () {
    // This feature is still prefixed in Safari
    window.AudioContext = window.AudioContext || window.webkitAudioContext;
    if(window.AudioContext){
        return true;
    }
    else {
        return false;
    }
};

var audioContext;
if(isAudioContextSupported()) {
    audioContext = new window.AudioContext();
}