util: add fast path to stripVTControlCharacters

[privatenumber]

Problem

stripVTControlCharacters always runs a regex replacement, even when the input contains no ANSI escape codes. This is the common case — most strings passed through are already plain text (e.g. checking/sanitizing user input, processing log lines that are mostly text).

Changes

Adds a StringPrototypeIncludes guard for ESC (\u001B) and CSI (\u009B) before the regex. Since all ANSI escape sequences start with one of these introducers, their absence means no ANSI codes exist and we can return the string immediately — skipping regex execution.

Based on the same optimization proposed in chalk/strip-ansi#54.

Also adds a benchmark and test coverage for the fast path, 7-bit ESC sequences, and 8-bit CSI sequences.

Benchmarks

cpu: Apple M2 Max, runtime: node v23.11.0 (arm64-darwin)

Isolated component test showing speedup scaling with string length for non-ANSI input:

Length	Before	After	Speedup
50 chars	40 ns	20 ns	2.0x
200 chars	124 ns	35 ns	3.6x
1,000 chars	414 ns	67 ns	6.2x
3,000 chars	1,337 ns	201 ns	6.7x
10,000 chars	4,683 ns	739 ns	6.3x
50,000 chars	23,949 ns	2,755 ns	8.7x
100,000 chars	49,957 ns	5,719 ns	8.7x

ANSI input has negligible overhead from the includes check.

[nodejs-github-bot]

Review requested:

• @nodejs/performance

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.73%. Comparing base (9cc7fcc) to head (003511d).
⚠️ Report is 1 commits behind head on main.

Additional details and impacted files

@@            Coverage Diff             @@
##             main   #61833      +/-   ##
==========================================
+ Coverage   89.72%   89.73%   +0.01%     
==========================================
  Files         675      675              
  Lines      204797   204801       +4     
  Branches    39344    39348       +4     
==========================================
+ Hits       183752   183788      +36     
+ Misses      13324    13282      -42     
- Partials     7721     7731      +10     

Files with missing lines	Coverage Δ
lib/internal/util/inspect.js	99.67% <100.00%> (+<0.01%)	⬆️

... and 33 files with indirect coverage changes

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[addaleax]

Can you leave a comment in the source about why this short-circuiting is added? Because it still "looks" redundant when just reading the source.

[gurgunday]

You are doing two passes here, why not use a simple regex here that only checks these 2 characters in one pass?

Suggested change

	if (!StringPrototypeIncludes(str, '\u001B') &&
	!StringPrototypeIncludes(str, '\u009B'))
	return str;
	if (!RegExpPrototypeTest(/[\u001B\u009B]/, str))
	return str;

Did you test the performance of this? I think this would be even faster

[RafaelGSS]

It's unlikely that a Regex test will be faster.

Possibly this is better:

if (StringPrototypeIndexOf(str, '\u001B') === -1 &&
    StringPrototypeIndexOf(str, '\u009B') === -1)

[RafaelGSS]

Please, share nodejs benchmark results. The one you attached in the PR description doesn't seem Node.js one.

[RafaelGSS]

It's unlikely that a Regex test will be faster.

Possibly this is better:

if (StringPrototypeIndexOf(str, '\u001B') === -1 &&
    StringPrototypeIndexOf(str, '\u009B') === -1)