[proof of concept] add 'hovertext' attribute

Author: etpinard

src/traces/scatter/arrays_to_calcdata.js

@@ -16,6 +16,7 @@ var Lib = require('../../lib');
 module.exports = function arraysToCalcdata(cd, trace) {
 
     Lib.mergeArray(trace.text, cd, 'tx');
+    Lib.mergeArray(trace.hovertext, cd, 'htx');
     Lib.mergeArray(trace.customdata, cd, 'data');
     Lib.mergeArray(trace.textposition, cd, 'tp');
     if(trace.textfont) {

src/traces/scatter/attributes.js

@@ -83,7 +83,23 @@ module.exports = {
             'If a single string, the same string appears over',
             'all the data points.',
             'If an array of string, the items are mapped in order to the',
-            'this trace\'s (x,y) coordinates.'
+            'this trace\'s (x,y) coordinates.',
+            'If trace `hoverinfo` contains a *text* flag and *hovertext* is not set,',
+            'these elements will be seen in the hover labels.'
+        ].join(' ')
+    },
+    hovertext: {
+        valType: 'string',
+        role: 'info',
+        dflt: '',
+        arrayOk: true,
+        description: [
+            'Sets hover text elements associated with each (x,y) pair.',
+            'If a single string, the same string appears over',
+            'all the data points.',
+            'If an array of string, the items are mapped in order to the',
+            'this trace\'s (x,y) coordinates.',
+            'To be seen, trace `hoverinfo` must contain a *text* flag.'
         ].join(' ')
     },
     mode: {

src/traces/scatter/defaults.js

@@ -38,6 +38,7 @@ module.exports = function supplyDefaults(traceIn, traceOut, defaultColor, layout
 
     coerce('customdata');
     coerce('text');
+    coerce('hovertext');
     coerce('mode', defaultMode);
     coerce('ids');
 

src/traces/scatter/hover.js

@@ -72,7 +72,9 @@ module.exports = function hoverPoints(pointData, xval, yval, hovermode) {
                 yLabelVal: di.y
             });
 
-            if(di.tx) pointData.text = di.tx;
+            if(di.htx) pointData.text = di.htx;
+            else if(trace.hovertext) pointData.text = trace.hovertext;
+            else if(di.tx) pointData.text = di.tx;
             else if(trace.text) pointData.text = trace.text;
 
             ErrorBars.hoverInfo(di, trace, pointData);