feat: add option to transform tooltip text

Author: ealves-pt

README.md

@@ -12,6 +12,8 @@ var defaultOptions = {
   //e.g. 4000 => €4,000
   tooltipFnc: undefined, //accepts function
   //build custom tooltip
+  transformTooltipTextFnc: undefined, // accepts function
+  // transform tooltip text
   class: undefined, // accecpts 'class1', 'class1 class2', etc.
   //adds class(es) to tooltip wrapper
   appendToBody: false //accepts true or false

dist/chartist-plugin-tooltip.js

@@ -31,14 +31,6 @@
       appendToBody: false,
       class: undefined,
       pointClass: 'ct-point'
-      // showTooltips: true,
-      // tooltipEvents: ['mousemove', 'touchstart', 'touchmove'],
-      // labelClass: 'ct-label',
-      // labelOffset: {
-      //   x: 0,
-      //   y: -10
-      // },
-      // textAnchor: 'middle'
     };
 
     Chartist.plugins = Chartist.plugins || {};
@@ -91,10 +83,14 @@
           var hasMeta = !!meta;
           var value = $point.getAttribute('ct:value');
 
-          if (options.tooltipFnc) {
+          if (options.transformTooltipTextFnc && typeof options.transformTooltipTextFnc === 'function') {
+            value = options.transformTooltipTextFnc(value);
+          }
+
+          if (options.tooltipFnc && typeof options.tooltipFnc === 'function') {
             tooltipText = options.tooltipFnc(meta, value);
           } else {
-            if(options.metaIsHTML){
+            if (options.metaIsHTML) {
               var txt = document.createElement("textarea");
               txt.innerHTML = meta;
               meta = txt.value;