fix: stackOffset expand should not override numerical XAxis domain by SeaL773 · Pull Request #7152 · recharts/recharts

SeaL773 · 2026-03-21T17:41:41Z

Summary

Root Cause

In combineAxisDomain (src/state/selectors/axisSelectors.ts), when stackOffsetType === 'expand', the function returns [0, 1] for all non-category axes. However, the expand domain should only apply to the value axis (YAxis in horizontal layout), not the base axis (XAxis).
When XAxis type='number' is set, it skips the type === 'category' branch and incorrectly hits the expand domain shortcut, causing the XAxis domain to become [0, 1] while actual data values are far outside this range.

Fix

Added isCategorical check (already computed in the function):```diff

if (stackOffsetType === 'expand') {

if (stackOffsetType === 'expand' && !isCategorical) {


## Tests Added
3 new tests in `test/chart/AreaChart.stacked.spec.tsx`:
- Area curves render when XAxis type is number with expand offset
- Y axis domain is correctly `[0, 1]`
- X axis domain is NOT overridden to `[0, 1]`

All 38 tests pass.

<!-- This is an auto-generated comment: release notes by coderabbit.ai -->

## Summary by CodeRabbit

* **Bug Fixes**
  * Corrected axis domain calculation for stacked area charts with categorical X-axes when using the 'expand' stack offset setting.

<!-- end of auto-generated comment: release notes by coderabbit.ai -->

When stackOffset='expand' is used with XAxis type='number', the combineAxisDomain function was incorrectly returning [0, 1] for the X axis domain. The expand domain should only apply to the value axis (Y axis in horizontal layout), not the categorical axis. This caused all data points to be mapped outside the visible chart area, resulting in nothing being rendered. The fix adds an isCategorical check (already computed in the function) to ensure expandDomain only applies to the value axis. Fixes recharts#6517

coderabbitai · 2026-03-21T17:41:58Z

Walkthrough

Modified the combineAxisDomain function in axisSelectors to conditionally apply the expand domain only when the stack offset type is 'expand' and the axis is not categorical. Added a test case for numeric X-axis with stacked expand charts to validate the fix.

Changes

Cohort / File(s)	Summary
Axis Selector Logic `src/state/selectors/axisSelectors.ts`	Updated `combineAxisDomain` to return `expandDomain` only when `stackOffsetType === 'expand'` AND axis is non-categorical; otherwise returns `numericalDomain`.
Stacked Area Chart Tests `test/chart/AreaChart.stacked.spec.tsx`	Replaced placeholder test with active test suite for numeric X-axis with `stackOffset="expand"`, verifying Y-axis domain is `[0, 1]` and X-axis domain is not overridden.

Estimated code review effort

🎯 2 (Simple) | ⏱️ ~10 minutes

Possibly related PRs

Ts strict #6750: Changes axisSelectors domain logic for stack offset handling and axis type differentiation.

Suggested reviewers

PavelVanecek
ckifer

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title 'fix: stackOffset expand should not override numerical XAxis domain' accurately and specifically describes the main bug fix in the changeset.
Description check	✅ Passed	The PR description provides clear summary, root cause analysis, fix explanation, and test details. All key sections are covered with specific information about the issue and solution.
Linked Issues check	✅ Passed	The PR directly addresses issue `#6517` by adding the isCategorical check to prevent expand domain from overriding numerical XAxis domains, with corresponding tests verifying the fix.
Out of Scope Changes check	✅ Passed	All changes are directly related to fixing the expand domain issue for numerical XAxis. No unrelated modifications or out-of-scope changes detected.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.

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🧹 Nitpick comments (1)

test/chart/AreaChart.stacked.spec.tsx (1)

1292-1297: Tighten the X-axis assertion and verify selector call count.

not.toEqual([0, 1]) is permissive. Prefer asserting the concrete expected domain from numericData and include a call-count check on the spy for selector stability.

Suggested test refinement

-      it('should not override X axis domain to [0, 1]', () => {
+      it('should keep numeric X axis domain from data', () => {
         const { spy } = renderTestCase(state => selectAxisDomain(state, 'xAxis', defaultAxisId, false));
-        const result = spy.mock.lastCall?.[0];
-        expect(result).toBeDefined();
-        expect(result).not.toEqual([0, 1]);
+        expect(spy).toHaveBeenCalledTimes(1);
+        expectLastCalledWith(spy, [1, 3]);
       });

As per coding guidelines, "Verify the number of selector calls using the spy object from createSelectorTestCase to spot unnecessary re-renders and improve performance."

🤖 Prompt for AI Agents

Verify each finding against the current code and only fix it if needed.

In `@test/chart/AreaChart.stacked.spec.tsx` around lines 1292 - 1297, The test
currently only asserts the X-axis domain is not [0,1]; update it to assert the
concrete expected domain computed from the fixture numericData (use the same
min/max logic the selector uses) and verify the selector invocation count for
stability: after calling renderTestCase with selectAxisDomain and args ('xAxis',
defaultAxisId, false) assert spy.mock.lastCall[0] equals the computed expected
domain and assert spy.mock.calls.length equals the expected number of selector
evaluations (use the spy returned by createSelectorTestCase/renderTestCase to
check call count).

🤖 Prompt for all review comments with AI agents

Verify each finding against the current code and only fix it if needed.

Nitpick comments:
In `@test/chart/AreaChart.stacked.spec.tsx`:
- Around line 1292-1297: The test currently only asserts the X-axis domain is
not [0,1]; update it to assert the concrete expected domain computed from the
fixture numericData (use the same min/max logic the selector uses) and verify
the selector invocation count for stability: after calling renderTestCase with
selectAxisDomain and args ('xAxis', defaultAxisId, false) assert
spy.mock.lastCall[0] equals the computed expected domain and assert
spy.mock.calls.length equals the expected number of selector evaluations (use
the spy returned by createSelectorTestCase/renderTestCase to check call count).

ℹ️ Review info

⚙️ Run configuration

Configuration used: Organization UI

Review profile: CHILL

Plan: Pro

Run ID: 40eaf213-c05a-4183-a955-43b1ea686ffa

📥 Commits

Reviewing files that changed from the base of the PR and between b39edbf and 728bf6b.

📒 Files selected for processing (2)

src/state/selectors/axisSelectors.ts
test/chart/AreaChart.stacked.spec.tsx

codecov · 2026-03-21T23:15:37Z

Bundle Report

Changes will increase total bundle size by 93 bytes (0.0%) ⬆️. This is within the configured threshold ✅

Detailed changes

Bundle name	Size	Change
recharts/bundle-cjs	1.3MB	18 bytes (0.0%) ⬆️
recharts/bundle-es6	1.13MB	18 bytes (0.0%) ⬆️
recharts/bundle-umd	546.68kB	3 bytes (0.0%) ⬆️
recharts/bundle-treeshaking-polar	448.01kB	18 bytes (0.0%) ⬆️
recharts/bundle-treeshaking-treemap	354.03kB	18 bytes (0.01%) ⬆️
recharts/bundle-treeshaking-cartesian	643.62kB	18 bytes (0.0%) ⬆️

Affected Assets, Files, and Routes:

view changes for bundle: recharts/bundle-treeshaking-treemap

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
`bundle.js`	18 bytes	354.03kB	0.01%

view changes for bundle: recharts/bundle-es6

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
`state/selectors/axisSelectors.js`	18 bytes	59.24kB	0.03%

view changes for bundle: recharts/bundle-treeshaking-cartesian

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
`bundle.js`	18 bytes	643.62kB	0.0%

view changes for bundle: recharts/bundle-umd

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
`Recharts.js`	3 bytes	546.68kB	0.0%

view changes for bundle: recharts/bundle-cjs

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
`state/selectors/axisSelectors.js`	18 bytes	69.27kB	0.03%

view changes for bundle: recharts/bundle-treeshaking-polar

Assets Changed:

Asset Name	Size Change	Total Size	Change (%)
`bundle.js`	18 bytes	448.01kB	0.0%

codecov · 2026-03-21T23:19:28Z

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 89.61%. Comparing base (b39edbf) to head (728bf6b).
⚠️ Report is 3 commits behind head on main.

Additional details and impacted files

@@           Coverage Diff           @@
##             main    #7152   +/-   ##
=======================================
  Coverage   89.61%   89.61%           
=======================================
  Files         536      536           
  Lines       40479    40479           
  Branches     5519     5519           
=======================================
  Hits        36275    36275           
  Misses       4196     4196           
  Partials        8        8

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PavelVanecek · 2026-03-22T03:10:35Z

Hi @SeaL773 how did you test this change? Do you have a repro, and screenshots before/after?

SeaL773 · 2026-03-22T05:04:07Z

Hi @SeaL773 how did you test this change? Do you have a repro, and screenshots before/after?

Hi @PavelVanecek, thanks for the review!

The StackBlitz from #6517 demonstrates the bug: https://stackblitz.com/edit/j22xpcdb?file=src%2FExample.tsx

Before: stackOffset="expand" with <XAxis type="number"> renders an empty chart. The XAxis domain is incorrectly overridden to [0, 1]:

After (with fix): Removing type="number" from the same StackBlitz shows the chart renders correctly, the fix ensures type="number" behaves the same way by not overriding the XAxis domain.

Tests included in this PR (test/chart/AreaChart.stacked.spec.tsx):

Test evidence (before/after):

Without fix, test fails:
✓ should render area curves when XAxis type is number (19ms)
✓ should have Y axis domain [0, 1] for expand offset (21ms)
✗ should not override X axis domain to [0, 1] (27ms)   ← FAIL

Tests: 1 failed | 37 passed (38)

With fix, all tests pass:
✓ should render area curves when XAxis type is number
✓ should have Y axis domain [0, 1] for expand offset
✓ should not override X axis domain to [0, 1]

Tests: 38 passed (38)

PavelVanecek · 2026-03-22T05:41:06Z

This is what the example looks like after the fix:

because numerical axis goes to [0, auto] by default

If I switch to <XAxis type="number" dataKey="ts" domain={['dataMin', 'dataMax']} /> I get:

Which isn't a very pretty chart but it does render.

coderabbitai bot reviewed Mar 21, 2026

View reviewed changes

PavelVanecek approved these changes Mar 22, 2026

View reviewed changes

PavelVanecek merged commit 86ca8de into recharts:main Mar 22, 2026
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fix: stackOffset expand should not override numerical XAxis domain#7152

fix: stackOffset expand should not override numerical XAxis domain#7152
PavelVanecek merged 1 commit intorecharts:mainfrom
SeaL773:fix/expand-domain-number-xaxis

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