/**
 * Generate a cryptographically secure random string using the specified number
 * of bytes then encode with base64.
 *
 * Base64 encodes 6 bits per character and pads with = so the length will not
 * equal the number of randomly generated bytes.
 * @see <https://developer.mozilla.org/en-US/docs/Glossary/Base64#encoded_size_increase>
 */
export const generateRandomString = (bytes: number): string => {
	const byteArr = window.crypto.getRandomValues(new Uint8Array(bytes));
	// The types for `map` don't seem to support mapping from one array type to
	// another and `String.fromCharCode.apply` wants `number[]` so loop like this
	// instead.
	const strArr: string[] = [];
	for (const byte of byteArr) {
		strArr.push(String.fromCharCode(byte));
	}
	return btoa(strArr.join(""));
};