feat(wasm)!: native JS arrays via emscripten::val (replaces VectorDouble)

[ibell]

Summary

Replaces the embind VectorDouble/VectorString wrapper classes on the JS binding surface with native JavaScript arrays via emscripten::val.

Before

var v = new coolprop.VectorDouble();
v.push_back(0.4); v.push_back(0.6);
AS.set_mole_fractions(v);
v.delete();

var z = AS.get_mole_fractions();
console.log(z.get(0).value(), z.get(1).value(), z.size());
z.delete();

After

AS.set_mole_fractions([0.4, 0.6]);

var z = AS.get_mole_fractions();
console.log(z[0], z[1], z.length);

Same shape for get_phase_envelope_data() — returns a plain JS object whose fields (T, p, …) are native arrays. No .delete() calls needed for vector returns; standard JS GC handles them.

Two thin helpers in src/emscripten_interface.cxx do the conversion:

template <class T>
val vec_to_js_array(const std::vector<T>& v);
std::vector<double> js_array_to_vec(const val& arr);

Drops the register_vector/register_optional/value_object registrations, the #include <optional>, and the set_mole_fractions_double/_mass_fractions_double/_volu_fractions_double EMSCRIPTEN-only wrappers from include/AbstractState.h (no longer needed — the val→vector conversion happens in the lambda). The direct internal::_embind_register_optional call from PR #2974 (CoolProp-71a.8) is also gone with this refactor — no more optional<double> registration dependency.

Why this doesn't bump emsdk

The original motivation was to also unblock the emcc 5.x migration (CoolProp-71a.2) by removing the optional<double> dependency that breaks emcc's EMBIND_AOT path. Investigation showed AOT still fails against our binding shape at the link-time <<< EMBIND_AOT_INVOKERS >>> substitution (tsgen.js itself succeeds; the sentinel is missing from the final JS template). The Dockerfile + CI workflow stay pinned to emsdk 4.0.12. CoolProp-71a.2 stays open with this finding documented in the bead.

Breaking change

JS callers using the prior VectorDouble pattern will need to update (see Summary above). Changelog entry added under "Behavior changes (potentially breaking)".

Test plan

• cd wrappers/Javascript && docker compose run --rm runner against pinned emsdk 4.0.12 links cleanly
• node test_wasm.mjs exits 0 with all 5 sections passing — including:
  • mixture composition round-trip: get_mole_fractions() returns [0.4, 0.6] (real JS Array)
  • envelope mid-point: env.T[107] and env.p[107] read directly
• CI Javascript library workflow green

🤖 Generated with Claude Code

Summary by CodeRabbit

• New Features

  • JavaScript/WASM API now uses native JavaScript arrays for composition vectors and phase-envelope data. Setters accept arrays directly, and getters return native arrays, improving the developer experience.

• Documentation

  • Updated changelog documenting JavaScript API behavior changes.

[coderabbitai]

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ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro Plus

Run ID: aef4423f-0582-4e89-9b77-00ca73b1979f

📥 Commits

Reviewing files that changed from the base of the PR and between 2228c28 and 3859da2.

📒 Files selected for processing (5)

• Web/coolprop/changelog.rst
• include/AbstractState.h
• src/emscripten_interface.cxx
• wrappers/Javascript/Dockerfile
• wrappers/Javascript/test_wasm.mjs

💤 Files with no reviewable changes (1)

• include/AbstractState.h

---

📝 Walkthrough

Walkthrough

This PR migrates the CoolProp JavaScript/WASM interface from embind-managed vector wrapper types (VectorDouble, VectorString) to native JavaScript arrays. The change includes conversion utilities, updated bindings for composition fractions and phase envelopes, header cleanup, and test validation of the new array-based API surface.

Changes

WASM Vector to Native Array Binding Migration

Layer / File(s)	Summary
API Change Documentation Web/coolprop/changelog.rst	Changelog entry documents the shift from embind wrapper types to native JS arrays for composition vectors and phase-envelope data, with setters accepting and getters returning plain arrays.
Header Cleanup include/AbstractState.h	Removes the Emscripten-only set_mole_fractions_double, set_mass_fractions_double, and set_volu_fractions_double wrapper methods that were used for embind overload disambiguation.
Emscripten Binding Implementation src/emscripten_interface.cxx	Adds vec_to_js_array and js_array_to_vec conversion helpers; updates fraction setters to accept emscripten::val JS arrays and convert to std::vector; updates fraction getters to return native JS arrays; rebinds get_phase_envelope_data to a lambda returning a plain JS object with per-field native arrays.
Test Updates & Build Context wrappers/Javascript/test_wasm.mjs, wrappers/Javascript/Dockerfile	Integration tests now use native JS arrays directly for composition and phase-envelope access, eliminating VectorDouble construction and manual element access; Dockerfile comment updated to document current version pinning reason (EMBIND_AOT migration issue).

Poem

A wrapper falls away, arrays rise so bright,
No more embind vectors wrapping up the night,
JavaScript embraces nature's native form,
Each fraction and phase data, plain and warm! 🐰✨

🚥 Pre-merge checks | ✅ 4 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 50.00% which is insufficient. The required threshold is 80.00%.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (4 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title accurately summarizes the main change: replacing embind VectorDouble wrapper classes with native JavaScript arrays using emscripten::val. It is specific, concise, and directly reflects the primary objective of the changeset across all modified files.
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.

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✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch ihb/wasm-val-arrays-emcc5

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