Convert buffers of one word-length to another

bytesTransfer.js

function transferBytes(inputBuffer, inputLength, inputWordSize, wordSize, create) {
	inputWordSize |= 0;
	const inputBytes = inputLength * inputWordSize;
	const inputBitsize = inputWordSize << 3;
	
	wordSize |= 0;
	const bytes = (inputBytes - 1 & -wordSize) + wordSize;
	const bitsize = wordSize << 3;
	
	const buffer = create(bytes, bytes / wordSize);
	
	let inputIndex = -1;
	let byteIndex = 0;
	let word;
	let alignment = 0;
	let output = 0;
	for (let index = 0; index < bytes; ++index) {
		if (alignment <= 0) {
			word = inputBuffer(++inputIndex);
			alignment = inputBitsize;
		}
		alignment -= 8;
		
		if ((index / wordSize | 0) > byteIndex) {
			buffer(byteIndex, output);
			++byteIndex;
			output = 0;
		}
		else
			output <<= 8;
			
		output |= word >> alignment & 255;
	}
	
	if (output)
		buffer(byteIndex, output);
}

demoWrappers.js

function from8ToString(buffer) {
	let output = '';
	transferBytes(
		(index) => (buffer[index]),
		buffer.length,
		1,
		2,
		(bytes, length) => {
			return (index, word) => { output += String.fromCharCode(word) };
		}
	);
	return output;
}
function from32To16(buffer) {
	let output;
	transferBytes(
		(index) => (buffer[index]),
		buffer.length,
		4,
		2,
		(bytes, length) => {
			output = new Uint16Array(length);
			return (index, word) => { output[index] = word };
		}
	);
	return output;
}
function fromStringTo32(string) {
	let output;
	transferBytes(
		string.charCodeAt.bind(string),
		string.length,
		2,
		4,
		(bytes, length) => {
			output = new Uint32Array(new ArrayBuffer(bytes));
			return (index, word) => { output[index] = word };
		}
	);
	return output;
}
function fromStringTo16(string) {
	let output;
	transferBytes(
		string.charCodeAt.bind(string),
		string.length,
		2,
		2,
		(bytes, length) => {
			output = new Uint16Array(new ArrayBuffer(bytes));
			return (index, word) => { output[index] = word };
		}
	);
	return output;
}
function fromStringTo8(string) {
	let output;
	transferBytes(
		string.charCodeAt.bind(string),
		string.length,
		2,
		1,
		(bytes, length) => {
			output = new Uint8Array(new ArrayBuffer(bytes));
			return (index, word) => { output[index] = word };
		}
	);
	return output;
}

fromStringTo16('aaaa')
//Uint16Array(4) [97, 97, 97, 97]
fromStringTo16('aazaa')
//Uint16Array(5) [97, 97, 122, 97, 97]

fromStringTo8('aazaa')
//Uint8Array(10) [0, 97, 0, 97, 0, 122, 0, 97, 0, 97]
from8ToString(fromStringTo8('aazaa'))
//'aazaa'

fromStringTo32('azzaa')
//Uint32Array(3) [6357114, 7995489, 6356992]
fromStringTo32('aazzaa')
//Uint32Array(3) [6357089, 7995514, 6357089]
fromStringTo32('aazza')
//Uint32Array(3) [6357089, 7995514, 6356992]
fromStringTo32('aazz')
//Uint32Array(2) [6357089, 7995514]

fromStringTo32('aazza')
//Uint32Array(3) [6357089, 7995514, 6356992]
from32To16(fromStringTo32('aazza'))
//Uint16Array(6) [97, 97, 122, 122, 97, 0]
fromStringTo16('aazza')
//Uint16Array(5) [97, 97, 122, 122, 97]