Fix for #6614

draftlogs/6615_fix.md

@@ -0,0 +1,2 @@
+- Fix to prevent accessing undefined (hoverText.hoverLabels) in case all currently shown markers have hoverinfo: "none" [#6614]([https://github.com/plotly/plotly.js/pull/5854](https://github.com/plotly/plotly.js/issues/6614)),
+   with thanks to @Domino987 for the contribution!

src/components/fx/hover.js

@@ -1126,7 +1126,7 @@ function createHoverText(hoverData, opts) {
         container.selectAll('g.hovertext').remove();
         var groupedHoverData = hoverData.filter(function(data) {return data.hoverinfo !== 'none';});
         // Return early if nothing is hovered on
-        if(groupedHoverData.length === 0) return;
+        if(groupedHoverData.length === 0) return [];
 
         // mock legend
         var hoverlabel = fullLayout.hoverlabel;

test/jasmine/tests/hover_label_test.js

@@ -4726,6 +4726,40 @@ describe('hovermode: (x|y)unified', function() {
         .then(done, done.fail);
     });
 
+    it('should not fail if only hoverinfo: "none" are current visible', function(done) {
+        Plotly.newPlot(gd, {
+            data: [{
+                name: 'A',
+                x: [1, 100],
+                y: [1, 1]
+            }, {
+                name: 'B',
+                y: [1],
+                x: [50],
+                hoverinfo: 'none'
+            }],
+            layout: {
+                xaxis: {range: [40, 60]},
+                hovermode: 'x unified',
+                showlegend: false,
+                width: 500,
+                height: 500,
+                margin: {
+                    t: 50,
+                    b: 50,
+                    l: 50,
+                    r: 50
+                }
+            }
+        })
+        .then(function() {
+            _hover(gd, { xpx: 200, ypx: 200 });
+            expect(gd._hoverdata, undefined);
+            assertHoverLabelContent({});
+        })
+        .then(done, done.fail);
+    });
+
     it('y unified should work for x/y cartesian traces', function(done) {
         var mockCopy = Lib.extendDeep({}, mock);
         mockCopy.layout.hovermode = 'y unified';