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Expand ECMAScript implementation: Add integer conversions and fundamental operations #12687

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@Copilot Copilot AI commented Jul 31, 2025 •
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This PR significantly expands the oxc_ecmascript crate by implementing missing ECMAScript abstract operations essential for JavaScript tooling.

What's Added

Integer Conversion Operations (9 total):

  • ToUint32, ToUint16 - Unsigned integer conversions for bitwise operations
  • ToInt8, ToInt16 - Signed integer conversions completing the family
  • ToUint8, ToUint8Clamp - 8-bit conversions for typed arrays (ToUint8Clamp uses banker's rounding)
  • ToLength - Array/string length conversion with MAX_SAFE_INTEGER clamping

Mathematical Operations:

  • MathAbs, MathFloor, MathCeil, MathRound - Core mathematical functions
  • MathMax, MathMin - Comparison operations with helper functions

String Operations:

  • StringSlice - String.prototype.slice with Unicode support
  • StringIncludes - String.prototype.includes with position parameter
  • StringStartsWith, StringEndsWith - String matching operations
  • StringRepeat - String.prototype.repeat with error handling
  • StringTrim, StringTrimStart, StringTrimEnd - Whitespace trimming

Fundamental Operations:

  • SameValue - Strict equality (distinguishes +0/-0, treats NaN as equal to itself)
  • SameValueZero - Like SameValue but treats +0 and -0 as equal

Implementation Details

All operations follow the ECMAScript specification precisely:

  • Proper handling of edge cases (NaN, Infinity, -0/+0)
  • Comprehensive test coverage (32 tests total)
  • Support for multiple numeric types (f64, i32, u32)
  • Unicode-aware string operations
  • Banker's rounding for ToUint8Clamp per specification

This brings oxc_ecmascript much closer to a complete implementation of core ECMAScript abstract operations, making it significantly more useful for JavaScript tooling that needs spec-compliant behavior.

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Copilot AI and others added 2 commits July 31, 2025 16:33
@Copilot @Boshen
Implement major missing ECMAScript functionalities
8e53a9a 
Co-authored-by: Boshen <1430279+Boshen@users.noreply.github.com>
@Copilot @Boshen
Complete comprehensive ECMAScript implementation with all essential o…
492d34b 
…perations

Co-authored-by: Boshen <1430279+Boshen@users.noreply.github.com>
@Copilot Copilot AI requested a review from Boshen July 31, 2025 16:55
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Boshen commented Aug 1, 2025

@copilot please continue

@Copilot @Boshen
Add additional ECMAScript integer conversion and fundamental operations
ff16191 
Co-authored-by: Boshen <1430279+Boshen@users.noreply.github.com>
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Copilot AI commented Aug 1, 2025

@copilot please continue

I've continued expanding the ECMAScript implementation by adding 5 more fundamental operations:

New Integer Conversions:

  • ToInt8 and ToInt16 - Complete the signed integer conversion family
  • ToUint8 and ToUint8Clamp - 8-bit unsigned conversions (ToUint8Clamp uses banker's rounding for typed arrays)

Fundamental Operations:

  • ToLength - Array/string length conversion with MAX_SAFE_INTEGER clamping
  • SameValue and SameValueZero - Strict equality comparisons (key difference: SameValue distinguishes +0/-0)

All 32 tests pass, bringing the total from 23 to 32 test functions. These operations are essential building blocks for JavaScript tooling and complete the core integer conversion family used throughout the ECMAScript specification.

ff16191

@Copilot Copilot AI changed the title [WIP] @oxc-project/oxc/files/crates/oxc_ecmascript implements the javascript specification, it contains javascript methods and constant evaluation. Add missing functionalities from the specification. Expand ECMAScript implementation: Add integer conversions and fundamental operations Aug 1, 2025
Copilot finished work on behalf of Boshen August 1, 2025 07:37
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codspeed-hq bot commented Aug 1, 2025

CodSpeed Instrumentation Performance Report

Merging #12687 will not alter performance

Comparing copilot/fix-9ac53b94-2a10-431e-99dc-59cb76b39b00 (7fd3324) with main (ce5876d)1

Summary

✅ 34 untouched benchmarks

Footnotes

  1. No successful run was found on main (e9b9488) during the generation of this report, so ce5876d was used instead as the comparison base. There might be some changes unrelated to this pull request in this report. ↩

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