From bfc7e8aa37801816fb2acd7bdd383034b7e45060 Mon Sep 17 00:00:00 2001
From: Uberti Davide <ubertidavide@users.noreply.github.com>
Date: Fri, 24 Jul 2026 19:38:28 +0200
Subject: [PATCH] fix(heatmap): add eventData handler for proper click event
 data

---
 src/traces/heatmap/event_data.js   | 16 +++++++++++
 src/traces/heatmap/index.js        |  1 +
 test/jasmine/tests/heatmap_test.js | 44 ++++++++++++++++++++++++++++++
 3 files changed, 61 insertions(+)
 create mode 100644 src/traces/heatmap/event_data.js

diff --git a/src/traces/heatmap/event_data.js b/src/traces/heatmap/event_data.js
new file mode 100644
index 00000000000..535350c5288
--- /dev/null
+++ b/src/traces/heatmap/event_data.js
@@ -0,0 +1,16 @@
+'use strict';
+
+module.exports = function eventData(out, pt) {
+    if ('index' in pt) {
+        out.pointNumber = pt.index;
+        out.pointIndex = pt.index;
+    }
+
+    if ('zLabelVal' in pt) {
+        out.z = pt.zLabelVal;
+    } else if ('z' in pt) {
+        out.z = pt.z;
+    }
+
+    return out;
+};
\ No newline at end of file
diff --git a/src/traces/heatmap/index.js b/src/traces/heatmap/index.js
index f60bcb39f28..fee2dec6c03 100644
--- a/src/traces/heatmap/index.js
+++ b/src/traces/heatmap/index.js
@@ -8,6 +8,7 @@ module.exports = {
     colorbar: require('./colorbar'),
     style: require('./style'),
     hoverPoints: require('./hover'),
+    eventData: require('./event_data'),
 
     moduleType: 'trace',
     name: 'heatmap',
diff --git a/test/jasmine/tests/heatmap_test.js b/test/jasmine/tests/heatmap_test.js
index ceb527f4132..7766223f733 100644
--- a/test/jasmine/tests/heatmap_test.js
+++ b/test/jasmine/tests/heatmap_test.js
@@ -1114,4 +1114,48 @@ describe('heatmap hover', function() {
             expect(pt).toEqual(undefined);
         });
     });
+
+    describe('heatmap event data', function() {
+        var gd;
+
+        beforeEach(function() {
+            gd = createGraphDiv();
+        });
+
+        afterEach(destroyGraphDiv);
+
+        it('should include 2D pointNumber and z value in plotly_click payload', function(done) {
+            var mockData = [{
+                type: 'heatmap',
+                z: [[1, 2], [3, 4]],
+                x: ['A', 'B'],
+                y: ['Row1', 'Row2']
+            }];
+
+            Plotly.newPlot(gd, mockData).then(function() {
+                var clickData = null;
+
+                gd.on('plotly_click', function(data) {
+                    clickData = data;
+                });
+
+                var mockClick = require('../assets/click');
+                var bBox = gd.getBoundingClientRect();
+
+                mockClick(bBox.left + 100, bBox.top + 300);
+
+                expect(clickData).not.toBeNull();
+                expect(clickData.points.length).toBe(1);
+
+                var pt = clickData.points[0];
+
+                expect(Array.isArray(pt.pointNumber)).toBe(true, 'pointNumber should be an array');
+                expect(pt.pointNumber).toEqual([0, 0], 'should point to the first row and col');
+                expect(pt.z).toBe(1, 'should extract the correct z value');
+
+                done();
+            }).catch(done.fail);
+        });
+    });
 });
+