AudioContext monkey patch that makes old style and new style names available simultaneously.

AudioContextMonkeyPatch.js

/* Copyright (c) 2013, Srikumar K. S. ([email protected])
 * All rights reserved.
 * 
 * Licensed under the MIT License - 
 *
 * Permission is hereby granted, free of charge, to any person obtaining a copy
 * of this software and associated documentation files (the "Software"), to deal
 * in the Software without restriction, including without limitation the rights
 * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
 * copies of the Software, and to permit persons to whom the Software is
 * furnished to do so, subject to the following conditions:
 * 
 * The above copyright notice and this permission notice shall be included in
 * all copies or substantial portions of the Software.
 * 
 * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
 * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
 * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
 * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
 * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
 * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN
 * THE SOFTWARE.
 * 
 * Usage: 
 *
 * Include this script as <script src="http://sriku.org/lib/AudioContext.js"></script>
 * or copy-paste the code into your JS lib files to use it.
 *
 * Description:
 *
 * This replaces the browser-provided AudioContext class with a wrapper that
 * supports legacy names in newer implementations and new names in older
 * implementations. This is so that new code can run in both new and old
 * implementations and old code can run in them as well without changes.
 *
 * When you run your code with this AudioContext, you'll get deprecation
 * warnings and prompts to move your code to the newer APIs ... which will
 * be available immediately even if you're working with a dated browser
 * implementation.
 */
;(function () {
    var GLOBAL = this;

    function alias(obj, oldName, newName) {
        obj[newName] = obj[newName] || obj[oldName];
        supportDeprecated(obj, oldName, newName);
    }

    function supportDeprecated(obj, oldName, newName) {
        var oldMethod = obj[oldName];
        obj[oldName] = function () {
            console.warn('Web Audio API: Deprecated name %s used. Use %s instead.', oldName, newName);
            obj[oldName] = oldMethod || obj[newName];
            return oldMethod.apply(this, arguments);
        };
    }

    GLOBAL.AudioContext = (function (AC) {
        'use strict';

        if (!AC) {
            console.warn('Web Audio API not supported on this client.');
            return undefined;
        }

        return function AudioContext() {
            var ac, AudioParam, AudioParamOld, BufferSource, Oscillator;

            if (arguments.length === 0) {
                // Realtime audio context.
                ac = new AC;
            } else if (arguments.length === 3) {
                // Offline audio context.
                ac = new AC(arguments[0], arguments[1], arguments[2]);
            } else {
                throw new Error('Invalid instantiation of AudioContext');
            }

            alias(ac, 'createGainNode', 'createGain');
            alias(ac, 'createDelayNode', 'createDelay');
            alias(ac, 'createJavaScriptNode', 'createScriptProcessor');

            // Find out the AudioParam prototype object.
            // Some older implementations keep an additional empty
            // interface for the gain parameter.
            AudioParam = Object.getPrototypeOf(ac.createGain().gain);
            AudioParamOld = Object.getPrototypeOf(AudioParam);
            if (AudioParamOld.setValueAtTime) {
                // Checking for the presence of setValueAtTime to find whether
                // it is the right prototype class is, I expect, more robust than
                // checking whether the class name is this or that. - Kumar
                console.warn('Implementation uses extra dummy interface for AudioGainParam. This will be removed.');
                AudioParam = AudioParamOld;
            }

            alias(AudioParam, 'setTargetValueAtTime', 'setTargetAtTime');

            // For BufferSource node, we need to also account for noteGrainOn.
            BufferSource = Object.getPrototypeOf(ac.createBufferSource());
            alias(BufferSource, 'noteOff', 'stop');
            if (BufferSource.start) {
                supportDeprecated(BufferSource, 'noteOn', 'start');
                supportDeprecated(BufferSource, 'noteGrainOn', 'start');
            } else {
                console.warn('Web Audio API: Only BufferSource.note[Grain]On available. Providing BufferSource.start.');
                BufferSource.start = function start(when, offset, duration) {
                    switch (arguments.length) {
                        case 1: return this.noteOn(when);
                        case 3: return this.noteGrainOn(when, offset, duration);
                        default: throw new Error('Invalid arguments to BufferSource.start');
                    }
                };
                supportDeprecated(BufferSource, 'noteOn', 'start');
                supportDeprecated(BufferSource, 'noteOff', 'stop');
            }


            Oscillator = Object.getPrototypeOf(ac.createOscillator());
            alias(Oscillator, 'noteOn', 'start');
            alias(Oscillator, 'noteOff', 'stop');

            return ac;
        };
    }(GLOBAL.AudioContext || GLOBAL.webkitAudioContext));

    GLOBAL.webkitAudioContext = function AudioContext() {
        console.warn('Use "new AudioContext" instead of "new webkitAudioContext".');
        switch (arguments.length) {
            case 0: return new GLOBAL.AudioContext();
            case 3: return new GLOBAL.AudioContext(arguments[0], arguments[1], arguments[2]);
            default: throw new Error('Invalid AudioContext creation');
        }
    };
}());