charsets.js

/**
 * SEE
 *   https://nodejs.org/docs/latest/api/buffer.html#buffer_buffers_and_character_encodings
 */

const CHARSETS = [
	'ascii'  , // For 7-bit ASCII data only. This encoding is fast and will strip the high bit if set.
	'utf8'   , // Multibyte encoded Unicode characters. Many web pages and other document formats use UTF-8.
	'utf-8'  ,
	'utf16le', // 2 or 4 bytes, little-endian encoded Unicode characters. Surrogate pairs (U+10000 to U+10FFFF) are supported.
	'ucs2'   , // Alias of 'utf16le'.
	'base64' , // Base64 encoding. When creating a Buffer from a string, this encoding will also correctly accept "URL and Filename Safe Alphabet" as specified in RFC4648, Section 5.
	'latin1' , // A way of encoding the Buffer into a one-byte encoded string (as defined by the IANA in RFC1345, page 63, to be the Latin-1 supplement block and C0/C1 control codes).
	'binary' , // Alias for 'latin1'.
	'hex'    , // Encode each byte as two hexadecimal characters.
];

const ALIAS = {
	'iso-8859-1': 'latin1',
};

module.exports = function(charset) {
	charset = charset.toLowerCase();
	if (ALIAS[charset]) {
		return ALIAS[charset];
	}
	else if (CHARSETS.includes(charset)) {
		return charset;
	}
	else {
		return null;
	}
};