Project Context — chubbyphp-typescript

PHP port of JavaScript's Array API with TypeScript-style generics. Keep behavior close to JavaScript Array; the test suite is the spec.

Where To Work

src/Arr.php is the main implementation.
tests/Unit/ArrTest.php is the main spec and is organized by JS API section order.
tests/Integration/DocumentationExamplesTest.php verifies the PHP examples in README.md and doc/Arr.md.
Update doc/Arr.md and README.md when public behavior changes.

Keep declare(strict_types=1);, typed properties, final classes, and the detailed PHPDoc generics/callable signatures in Arr.
Method ordering rule for Arr.php: (1) magic methods __*; (2) interface methods, in the order listed in implements; (3) the rest sorted by MDN JS Array order (statics first, then instance methods); (4) non-JS methods at the end. Mirror that order in tests/Unit/ArrTest.php, doc/Arr.md, and tests/Integration/DocumentationExamplesTest.php.
thisArg support is intentional: bind only non-static Closure callables; other callables ignore it.

Preserve sparse-array semantics. length may be greater than the number of populated indexes.
Holes read back as null through at(), values(), toArray(), and jsonSerialize(), but offsetExists()/isset() must still distinguish between missing indexes and explicit null values.
Favor JavaScript Array semantics over idiomatic PHP shortcuts.

Use Composer scripts as the default workflow: composer test:unit, composer test:integration, composer test:static-analysis, composer test:cs, or composer test.
PHPUnit runs in random order, so avoid hidden test coupling.
Keep every PHP example in README.md and doc/Arr.md executable and in sync with tests/Integration/DocumentationExamplesTest.php; add one integration test per documented example block.