Buffer.byteLength's implementation is not consistent with the documentation

[pd4d10]

node/lib/buffer.js

Lines 729 to 752 in f71166b

	function byteLength(string, encoding) {
	if (typeof string !== 'string') {
	if (isArrayBufferView(string) || isAnyArrayBuffer(string)) {
	return string.byteLength;
	}
	throw new ERR_INVALID_ARG_TYPE(
	'string', ['string', 'Buffer', 'ArrayBuffer'], string
	);
	}
	const len = string.length;
	const mustMatch = (arguments.length > 2 && arguments[2] === true);
	if (!mustMatch && len === 0)
	return 0;
	if (!encoding)
	return (mustMatch ? -1 : byteLengthUtf8(string));
	const ops = getEncodingOps(encoding);
	if (ops === undefined)
	return (mustMatch ? -1 : byteLengthUtf8(string));
	return ops.byteLength(string);
	}

In line 741 it checks the third argument mustMatch, which is not mentioned in the document

So I guess either the implementation or the documentation should be updated.

[Trott]

@nodejs/buffer @nodejs/documentation

[mscdex]

I believe it was part of a now outdated optimization. I think it can be removed from the code (the parts where mustMatch would've been true).