Run results for: CP437 decode

Test name	Executions per second
✓ append string	2,606,093 Ops/sec
from char code	372,856 Ops/sec
chunk 10	188,775 Ops/sec
chunk 100	177,590 Ops/sec
chunk 1000	156,504 Ops/sec
chunk 10000	85,905 Ops/sec

Script Preparation code:

var n = 8;
var arr = new Uint8Array(n);
for (let i = 0; i < n; ++i) {
  arr[i] = (Math.random() * 255) | 0;
}


const CP437 = "\0☺☻♥♦♣♠•◘○◙♂♀♪♫☼►◄↕‼¶§▬↨↑↓→←∟↔▲▼ !\"#$%&'()*+,-./0123456789:;<=>?@ABCDEFGHIJKLMNOPQRSTUVWXYZ[\\]^_`abcdefghijklmnopqrstuvwxyz{|}~⌂ÇüéâäàåçêëèïîìÄÅÉæÆôöòûùÿÖÜ¢£¥₧ƒáíóúñÑªº¿⌐¬½¼¡«»░▒▓│┤╡╢╖╕╣║╗╝╜╛┐└┴┬├─┼╞╟╚╔╩╦╠═╬╧╨╤╥╙╘╒╓╫╪┘┌█▄▌▐▀αßΓπΣσµτΦΘΩδ∞φε∩≡±≥≤⌠⌡÷≈°∙·√ⁿ²■ ".split("");
function convert_in_place(s)
{
	for (let k = 0; k < s.length; k++)
		s[k] = CP437[s[k]];
	return s;
}
function convert(buf)
{
	return convert_in_place(buf.slice());
}

function decodeAppend(buf)
{
	let result = "";
	for (let indexCharacter = 0; indexCharacter < buf.length; indexCharacter++) {
		result += CP437[buf[indexCharacter]];
	}
	return result;
}

function decodeFromCharCode(buf)
{
	const s = convert(buf);
	return String.fromCharCode.apply(null, s);
}

function decodeFromCharCode2(buf, chunk)
{
	let str = "";
	let pad = new Uint8Array(chunk);
	for(let k = 0; k < buf.length; k += chunk)
	{
		const remaining = buf.length - k;
		for (let i = 0; i < Math.min(chunk, remaining); i++)
			pad[i] = CP437[buf[k + i]];
		str += String.fromCharCode.apply(null, remaining < chunk ? pad.subarray(0, remaining) : pad);
	}
	return str;
}

Run results for: CP437 decode

append string

from char code

chunk 100

chunk 1000

chunk 10000

chunk 10