Refactor coercion logic

Author: alexshoe

src/components/shapes/defaults.js

@@ -65,8 +65,7 @@ function handleShapeDefaults(shapeIn, shapeOut, fullLayout) {
     var ySizeMode = coerce('ysizemode');
 
     // positioning
-    var axLetters = ['x', 'y'];
-    axLetters.forEach(function(axLetter) {
+    ['x', 'y'].forEach(axLetter => {
         var attrAnchor = axLetter + 'anchor';
         var sizeMode = axLetter === 'x' ? xSizeMode : ySizeMode;
         var gdMock = {_fullLayout: fullLayout};

src/components/shapes/helpers.js

@@ -61,15 +61,13 @@ exports.countDefiningCoords = function(shapeType, path) {
     var segments = path.match(constants.segmentRE);
     if(!segments) return 0;
 
-    var coordCount = 0;
-    segments.forEach(function(segment) {
+    return segments.reduce((coordCount, segment) => {
         // for each path command, check if there is a drawn coordinate
         var segmentType = segment.charAt(0);
         var hasDrawnX = constants.paramIsX[segmentType].drawn !== undefined;
         var hasDrawnY = constants.paramIsY[segmentType].drawn !== undefined;
-        if(hasDrawnX || hasDrawnY) coordCount++;
-    });
-    return coordCount;
+        return coordCount + (hasDrawnX || hasDrawnY ? 1 : 0);
+    }, 0);
 };
 
 exports.getDataToPixel = function(gd, axis, shift, isVertical, refType) {

src/plots/cartesian/axes.js

@@ -98,8 +98,7 @@ function expandRange(range) {
  *     but can be prefixed, like 'ax' for annotation's arrow x
  * dflt: the default to coerce to, or blank to use the first axis (falling back on
  *     extraOption if there is no axis)
- * extraOption: aside from existing axes with this letter, what non-axis value is allowed?
- *     Only required if it's different from `dflt`
+ * extraOption: fallback value, only required if it's different from `dflt`
  */
 axes.coerceRef = function(containerIn, containerOut, gd, attr, dflt, extraOption) {
     var axLetter = attr.charAt(attr.length - 1);
@@ -143,7 +142,7 @@ axes.coerceRefArray = function(containerIn, containerOut, gd, attr, dflt, extraO
 
     // Build the axis list, which we use to validate the axis references
     if(!dflt) dflt = axlist[0] || (typeof extraOption === 'string' ? extraOption : extraOption[0]);
-    axlist = axlist.concat(axlist.map(function(x) { return x + ' domain'; }));
+    axlist = axlist.concat(axlist.map(x => x + ' domain'));
     axlist = axlist.concat(extraOption ? extraOption : []);
 
     // Handle array length mismatch
@@ -178,6 +177,7 @@ axes.coerceRefArray = function(containerIn, containerOut, gd, attr, dflt, extraO
  */
 axes.getRefType = function(ar) {
     if(ar === undefined) { return ar; }
+    if(Array.isArray(ar)) { return 'array'; }
     if(ar === 'paper') { return 'paper'; }
     if(ar === 'pixel') { return 'pixel'; }
     if(/( domain)$/.test(ar)) { return 'domain'; } else { return 'range'; }