[nev21]

Performance

• arrSlice now uses _unwrapFunction("slice", ArrProto) rather than slicing its own arguments before calling slice (~16% faster in a V8 micro-benchmark and smaller). It still uses the value's own slice when present, but as it is now a const its name and length change
• createFnDeferredProxy, objExtend, deepExtend, the createCustomError base class call and the timer callback wrapper now pass their arguments object directly rather than copying it (objExtend ~29% faster). ES5 is the minimum runtime and every call has its own arguments object
• The arguments are still copied where they are kept or modified after the call returns (_createTimeoutWith and scheduleInterval for refresh()), with comments explaining why

Cyclic dependencies

• Move ICachedValue, ILazyValue, TimeoutOverrideFn, ClearTimeoutOverrideFn and TimeoutOverrideFuncs to helpers/types.ts, which has no imports, and re-export them from their original modules. This removes the type-level import cycle between cache, lazy, define, global, handler and timeout, without using import type (TypeScript v3.8)

Exported types now compile with TypeScript v3.4, as documented

• Add helpers/deep_types.ts: DeepPartial, DeepReadonly and DeepRequired now resolve arrays through new DeepPartialArray, DeepReadonlyArray and DeepRequiredArray interfaces, as a type alias can't reference itself as a type argument before v3.7. The resulting types are unchanged
• ObjDefinePropDescriptorMap is now Record<PropertyKey, ...>
• Add library-owned types for lib types that older compilers or an ES2015 lib don't provide:
  • IAsyncGeneratorFunction, used by isAsyncGenerator
  • IAsyncIterable and IAsyncIterator, used by isAsyncIterable. On TypeScript v4.3+ these are interchangeable with the native types. Older compilers using the ES2018 lib see any, so a value declared as a union with AsyncIterable is no longer narrowed on those versions
  • IIdleDeadline, IIdleRequestOptions and IdleCallbackFn, used by RequestIdleCallback and scheduleIdleCallback

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[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 99.22%. Comparing base (c76f017) to head (f5877c7).

Additional details and impacted files

@@           Coverage Diff           @@
##             main     #639   +/-   ##
=======================================
  Coverage   99.21%   99.22%           
=======================================
  Files         180      181    +1     
  Lines        5630     5688   +58     
  Branches     1297     1287   -10     
=======================================
+ Hits         5586     5644   +58     
  Misses         44       44           

Files with missing lines	Coverage Δ
lib/src/array/arrIndexOfSubset.ts	100.00% <ø> (ø)
lib/src/array/slice.ts	100.00% <100.00%> (ø)
lib/src/funcs/fnProxy.ts	100.00% <100.00%> (ø)
lib/src/helpers/base.ts	100.00% <100.00%> (ø)
lib/src/helpers/cache.ts	100.00% <100.00%> (ø)
lib/src/helpers/customError.ts	100.00% <100.00%> (ø)
lib/src/helpers/deep_types.ts	100.00% <100.00%> (ø)
lib/src/helpers/extend.ts	100.00% <100.00%> (ø)
lib/src/helpers/lazy.ts	100.00% <100.00%> (ø)
lib/src/helpers/types.ts	100.00% <ø> (ø)
... and 7 more

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[Copilot]

🟡 Changes recommended

A critical active finding remains because the common test suite references the ES2018-only AsyncGeneratorFunction type while compiling against ES2015 libraries, causing test compilation to fail before execution.

1 open issue

• Avoid ES2018-only type in common tests · New

_{Review effort: Lite}

[nevware21-bot]

Approved by nevware21-bot

[Copilot]

🔵 Needs a closer look

The changes span public declarations and runtime wrappers across multiple TypeScript versions, library targets, and browser/worker environments, requiring compatibility validation beyond the available snapshot checks.

1 open issue

• Avoid ES2018-only type in common tests

_{Review effort: Lite}

[nevware21-bot]

Approved by nevware21-bot

[Copilot]

🔵 Needs a closer look

Defer because the compatibility change requires validating declarations, assignability, and API-extractor output across the supported TypeScript and library-version matrix, which this review snapshot cannot verify.

No open issues 🎉

1 resolved since last review

• Avoid ES2018-only type in common tests

_{Review effort: Lite}