Fix autoskipped ticks messing up category axis (#4649)

diff --git a/src/core/core.scale.js b/src/core/core.scale.js
index dd99d0bdd70cd5c88789fac1593079f9ea211e4a..6f63b92dbd7e8b782e1a022de4eb7d3e26471cb4 100644 (file)
--- a/src/core/core.scale.js
+++ b/src/core/core.scale.js
@@ -626,7 +626,8 @@ module.exports = function(Chart) {
                                // Since we always show the last tick,we need may need to hide the last shown one before
                                shouldSkip = (skipRatio > 1 && i % skipRatio > 0) || (i % skipRatio === 0 && i + skipRatio >= tickCount);
                                if (shouldSkip && i !== tickCount - 1 || helpers.isNullOrUndef(tick.label)) {
-                                       continue;
+                                       // leave tick in place but make sure it's not displayed (#4635)
+                                       delete tick.label;
                                }
                                result.push(tick);
                        }
@@ -672,6 +673,11 @@ module.exports = function(Chart) {
                        var yTickEnd = options.position === 'bottom' ? me.top + tl : me.bottom;
 
                        helpers.each(ticks, function(tick, index) {
+                               // autoskipper skipped this tick (#4635)
+                               if (tick.label === undefined) {
+                                       return;
+                               }
+
                                var label = tick.label;
                                var lineWidth, lineColor, borderDash, borderDashOffset;
                                if (index === (typeof me.zeroLineIndex !== 'undefined' ? me.zeroLineIndex : 0) && (options.offset === gridLines.offsetGridLines)) {