A function that will create an audio context that bypasses the iOS sample rate mismatch bug

createAudioContext.js

/**
 * A function that will create an audio context that fixes
 * the iOS sample rate mismatch bug
 *
 * Author: Aaron George https://github.com/aarongeorge
 */

// Create Audio Context
const createAudioContext = (desiredSampleRate = 44100) => {
	
	// Deal with browser prefixes
	const AudioContext = window.AudioContext || window.webkitAudioContext
	
	// Create new audio context
	let audioContext = new AudioContext()
	
	// Regular expression that matches iOS devices
	const iOSRegex = new RegExp('iPhone|iPad|iPod', 'i')
	
	// Warm a `context`
	const warmContext = (context, sampleRate) => {
		
		// Create buffer and warmer source
		const buffer = context.createBuffer(1, 1, sampleRate)
		const warmer = context.createBufferSource()
		
		// Set `warmer.buffer` to `buffer`
		warmer.buffer = buffer
		
		// Connect `warmer`
		warmer.connect(context.destination)
		
		// Play `warmer`
		if (warmer.start) warmer.start(0)
		else if (warmer.noteOn) warmer.noteOn(0)
		
		// Disconnect `warmer`
		warmer.disconnect()
	}
	
	/**
	* There is a bug with iOS 6+ where you will get an incorrect sample rate
	* which causes distortion. The below checks for that and fixes it for you
	* by creating an audio context, destroying it, then creating a new one
	*/
	
	// Check if iOS
	if (iOSRegex.test(navigator.userAgent) && !window.MSStream) {
		
		// Warm the context
		warmContext(audioContext, desiredSampleRate)
		
		// `sampleRate` does not match `desiredSampleRate`
		if (audioContext.sampleRate !== desiredSampleRate) {
			
			// Close `audioContext`
			audioContext.close()
			
			// Create new `AudioContext`
			audioContext = new AudioContext()
			
			// Warm the new context
			warmContext(audioContext, desiredSampleRate)
		}
	}
	
	// Return `audioContext`
	return audioContext
}