BigInt to Buffer and Buffer to BigInt Nodejs

bigint.ts

function bigIntToBuffer(num: bigint, endian: 'be' | 'le') {
	const bytes: number[] = [];
	while (num > 0) {
		bytes.push(Number(num & 0xffn));
		num = num >> 8n;
	}
	return Buffer.from(endian === 'be' ? bytes.reverse() : bytes);
}

function bufferToBigInt(bytes: Buffer, endian: 'be' | 'le') {
	let num = 0n;
	for (let i = 0; i < bytes.length; i++) {
		num += BigInt(bytes[i]) << (8n * BigInt(endian === 'le' ? bytes.length - 1 - i : i));
	}
	return num;
}