Benchmark: split string by newlines (fixed)

Script Preparation code:

var NEWLINE = /\x0d\x0a|[\x0a\x0d\u2028\u2029]/gu;

function splitRegex(str) {
  const strings = [];

  NEWLINE.lastIndex = 0;
  let prevIndex = 0;
  let match;

  while (match = NEWLINE.exec(str)) {
    if (match.index > prevIndex) strings.push(str.substring(prevIndex, match.index));
    strings.push(match[0]);
    prevIndex = match.index + match[0].length;
    NEWLINE.lastIndex = prevIndex;
  }

  if (prevIndex < str.length) strings.push(str.substring(prevIndex, str.length));

  return strings;
}

function splitManual(str) {
	const strings = [];

	const cache1 = { i: -1 };
	const cache2 = { i: -1 };
	const cache3 = { i: -1 };
	const cache4 = { i: -1 };

	let position = 0;
	while (position < str.length) {
		if (cache1.i < 0) {
			const i = str.indexOf('\n', position);
			cache1.i = i < 0 ? str.length : i;
		}
		if (cache2.i < 0) {
			const i = str.indexOf('\r', position);
			cache2.i = i < 0 ? str.length : i;
		}
		if (cache3.i < 0) {
			const i = str.indexOf('\u2028', position);
			cache3.i = i < 0 ? str.length : i;
		}
		if (cache4.i < 0) {
			const i = str.indexOf('\u2029', position);
			cache4.i = i < 0 ? str.length : i;
		}

		let winner = cache1;
		if (cache2.i < winner.i) winner = cache2;
		if (cache3.i < winner.i) winner = cache3;
		if (cache4.i < winner.i) winner = cache4;

		const index = winner.i;
		if (index === str.length) {
			strings.push(str.substring(position, index));
			break;
		}

		let length = 1;
		if (winner === cache2 && str[index + 1] === '\n') {
			cache1.i = -1;
			length = 2;
		}

		if (index > position) {
			strings.push(str.substring(position, index));
		}
		strings.push(str.substring(index, index + length));

		position = index + length;
		winner.i = -1;
	}

	return strings;
}

var NO_NEWLINE = 'foobarbaz!'.repeat(1000);
var LAST_NEWLINE = 'foobarbaz!'.repeat(1000) + '\n';
var LAST_NEWLINE_WIN32 = 'foobarbaz!'.repeat(1000) + '\r\n';
var LAST_NEWLINE_UNICODE = 'foobarbaz!'.repeat(1000) + '\u2029';
var MANY_NEWLINES = 'foobarbaz\n'.repeat(1000);
var MANY_NEWLINES_WIN32 = 'foobarbaz\r\n'.repeat(1000);
var MANY_NEWLINES_UNICODE = 'foobarbaz\u2029'.repeat(1000);

// Side-effect to prevent code from being optimized away
window.result = 0;
var register = (results) => { window.result += (results[results.length - 1] || '').slice(-1).charCodeAt(0); };

Tests:

regex
register(splitRegex(NO_NEWLINE)); register(splitRegex(LAST_NEWLINE)); register(splitRegex(LAST_NEWLINE_WIN32)); register(splitRegex(LAST_NEWLINE_UNICODE)); register(splitRegex(MANY_NEWLINES)); register(splitRegex(MANY_NEWLINES_WIN32)); register(splitRegex(MANY_NEWLINES_UNICODE));
manual
register(splitManual(NO_NEWLINE)); register(splitManual(LAST_NEWLINE)); register(splitManual(LAST_NEWLINE_WIN32)); register(splitManual(LAST_NEWLINE_UNICODE)); register(splitManual(MANY_NEWLINES)); register(splitManual(MANY_NEWLINES_WIN32)); register(splitManual(MANY_NEWLINES_UNICODE));

Rendered benchmark preparation results:

Suite status: <idle, ready to run>

Previous results

Test case name	Result
regex
manual

Fastest: N/A

Slowest: N/A

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Latest run results:

Run details: (Test run date: one year ago)

User agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.15; rv:109.0) Gecko/20100101 Firefox/110.0

Browser/OS: Firefox 110 on Mac OS X 10.15

View result in a separate tab

Test name	Executions per second
regex	5687.4 Ops/sec
manual	4195.1 Ops/sec

split string by newlines (fixed) (version: 0)

Fastest way to split a string by newlines

Comparing performance of: regex vs manual

Created: one year ago by: Guest

Jump to the latest result

regex

manual

Suite status: <idle, ready to run>

Experimental features:

Fastest: N/A

Slowest: N/A