HF-270: Exporter honours evaluateNullToZero for bare empty cells

[marcin-kordas-hoc]

Fixes HF-270: the evaluateNullToZero config option is honoured by the interpreter (a formula reading an empty cell already coerces empty → 0) but was ignored by the Exporter, which always returned null for a bare empty cell read directly — so with the flag on, getSheetValues over [[null, '=A1']] gave [[null, 0]].

What changed

The Exporter's EmptyValue branch returns 0 when config.evaluateNullToZero is true, null otherwise. Default behaviour (flag off/absent) is byte-identical. ISBLANK still reports true for the bare empty cell either way. The CHANGELOG entry names the caveat: code relying on null from getCellValue to distinguish truly-empty from computed-zero under this flag should use ISBLANK instead.

Implemented independently from the task description (not taken from the fork referenced there).

Verification

Paired tests: hyperformula-tests@spike/hf270-null-to-zero (22 assertions across getCellValue / getSheetValues / ExportedCellChange / ISBLANK / default-off). tsc --noEmit clean, eslint --quiet clean.

🤖 Generated with Claude Code

---

Note

Medium Risk
Changes observable API output for consumers with evaluateNullToZero: true; default-off behavior is unchanged but callers relying on null for empty cells may need to adjust.

Overview
Aligns exported cell values with formula evaluation when evaluateNullToZero is enabled: bare empty cells now surface as 0 through the export layer instead of always null.

Exporter.exportValue checks config.evaluateNullToZero on EmptyValue and returns 0 or null accordingly, so getCellValue, sheet value getters, and ExportedCellChange match the interpreter’s empty→zero behavior. With the flag off, behavior is unchanged. Integrators who used null from getCellValue to distinguish empty from zero under this flag should use ISBLANK instead.

^{Reviewed by Cursor Bugbot for commit b1c3f34. Bugbot is set up for automated code reviews on this repo. Configure here.}

[qunabu]

Task linked: HF-270 evaluateNullToZero works inconsistently

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Status	Name	Latest Commit	Preview URL	Updated (UTC)
✅ Deployment successful! View logs	hyperformula-docs	b1c3f34	Commit Preview URL Branch Preview URL	Aug 31 2026, 05:19 AM

[github-actions]

Performance comparison of head (b1c3f34) vs base (114fd5d)

                                     testName |    base |    head | change
--------------------------------------------------------------------------
                                      Sheet A |  397.42 |  407.04 | +2.42%
                                      Sheet B |  132.11 |  136.03 | +2.97%
                                      Sheet T |  113.36 |  113.38 | +0.02%
                                Column ranges |   418.3 |   422.1 | +0.91%
                                Sorted lookup | 12774.3 | 12760.3 | -0.11%
Sheet A:  change value, add/remove row/column |   14.84 |   13.56 | -8.63%
 Sheet B: change value, add/remove row/column |  130.62 |  121.19 | -7.22%
                   Column ranges - add column |  134.71 |  136.89 | +1.62%
                Column ranges - without batch |  412.12 |  401.56 | -2.56%
                        Column ranges - batch |  105.38 |   99.08 | -5.98%

[marcin-kordas-hoc]

Paired tests PR: handsontable/hyperformula-tests#39 — merge it BEFORE this one.

[codecov]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 97.33%. Comparing base (114fd5d) to head (b1c3f34).

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #1738      +/-   ##
===========================================
+ Coverage    97.32%   97.33%   +0.01%     
===========================================
  Files          195      195              
  Lines        15739    15739              
  Branches      3390     3391       +1     
===========================================
+ Hits         15318    15320       +2     
+ Misses         421      419       -2     

Files with missing lines	Coverage Δ
src/Exporter.ts	89.33% <100.00%> (+2.66%)	⬆️

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