converting between Uint8Arrays and binary-encoded strings and word-arrays (for crypto purposes, with CryptoJS and NaCL)

gistfile1.js

/*
wordArray: { words: [..], sigBytes: words.length * 4 }
*/

// assumes wordArray is Big-Endian (because it comes from CryptoJS which is all BE)
// From: https://gist.github.com/creationix/07856504cf4d5cede5f9#file-encode-js
function convertWordArrayToUint8Array(wordArray) {
	var len = wordArray.words.length,
		u8_array = new Uint8Array(len << 2),
		offset = 0, word, i
	;
	for (i=0; i<len; i++) {
		word = wordArray.words[i];
		u8_array[offset++] = word >> 24;
		u8_array[offset++] = (word >> 16) & 0xff;
		u8_array[offset++] = (word >> 8) & 0xff;
		u8_array[offset++] = word & 0xff;
	}
	return u8_array;
}

// create a wordArray that is Big-Endian (because it's used with CryptoJS which is all BE)
// From: https://gist.github.com/creationix/07856504cf4d5cede5f9#file-encode-js
function convertUint8ArrayToWordArray(u8Array) {
	var words = [], i = 0, len = u8Array.length;

	while (i < len) {
		words.push(
			(u8Array[i++] << 24) |
			(u8Array[i++] << 16) |
			(u8Array[i++] << 8)  |
			(u8Array[i++])
		);
	}

	return {
		sigBytes: words.length * 4,
		words: words
	};
}

function convertUint8ArrayToBinaryString(u8Array) {
	var i, len = u8Array.length, b_str = "";
	for (i=0; i<len; i++) {
		b_str += String.fromCharCode(u8Array[i]);
	}
	return b_str;
}

function convertBinaryStringToUint8Array(bStr) {
	var i, len = bStr.length, u8_array = new Uint8Array(len);
	for (var i = 0; i < len; i++) {
		u8_array[i] = bStr.charCodeAt(i);
	}
	return u8_array;
}

const formatU8Afrom = Uint8Array.from.bind(Uint8Array);

const formatFromCC = String.fromCharCode.bind(String);

export function stringToUint8Array(str: string) {
  return formatU8Afrom(str, (c) => c.charCodeAt(0));
}

export function uint8ArrayToString(u8a: Uint8Array) {
  // cf. https://stackoverflow.com/questions/12710001/how-to-convert-uint8-array-to-base64-encoded-string/12713326#12713326
  const maxargs = 0x1000;
  const strs = [];
  for (let i = 0, l = u8a.length; i < l; i += maxargs) {
    strs.push(formatFromCC(...u8a.subarray(i, i + maxargs)));
  }
  return strs.join('');
}