Improved support for empty charts.

lib/morris.grid.coffee

@@ -96,24 +96,27 @@ class Morris.Grid extends Morris.EventEmitter
       if @options.ymax[0..3] is 'auto'
         # use Array.concat to flatten arrays and find the max y value
         if @options.ymax.length > 5
-          @ymax = Math.max parseInt(@options.ymax[5..], 10), ymax
+          @ymax = parseInt(@options.ymax[5..], 10)
+          @ymax = Math.max(ymax, @ymax) unless ymax is null
         else
-          @ymax = ymax
+          @ymax = if ymax isnt null then ymax else 0
       else
         @ymax = parseInt(@options.ymax, 10)
     else
       @ymax = @options.ymax
-    if typeof @options.ymin is 'string' and @options.ymin[0..3] is 'auto'
+    if typeof @options.ymin is 'string'
-      if @options.ymin.length > 5
+      if @options.ymin[0..3] is 'auto'
-        @ymin = Math.min parseInt(@options.ymin[5..], 10), ymin
+        if @options.ymin.length > 5
+          @ymin = parseInt(@options.ymin[5..], 10)
+          @ymin = Math.min(ymin, @ymin) unless ymin is null
+        else
+          @ymin = if ymin isnt null then ymin else 0
       else
-        @ymin = ymin
+        @ymin = parseInt(@options.ymin, 10)
-    else if typeof @options.ymin is 'string'
-      @ymin = parseInt(@options.ymin, 10)
     else
       @ymin = @options.ymin
     if @ymin is @ymax
-      if @ymin isnt 0 then @ymin -= 1
+      @ymin -= 1 if ymin
       @ymax += 1
 
     @yInterval = (@ymax - @ymin) / (@options.numLines - 1)

morris.js

@@ -391,9 +391,12 @@
       if (typeof this.options.ymax === 'string') {
         if (this.options.ymax.slice(0, 4) === 'auto') {
           if (this.options.ymax.length > 5) {
-            this.ymax = Math.max(parseInt(this.options.ymax.slice(5), 10), ymax);
+            this.ymax = parseInt(this.options.ymax.slice(5), 10);
+            if (ymax !== null) {
+              this.ymax = Math.max(ymax, this.ymax);
+            }
           } else {
-            this.ymax = ymax;
+            this.ymax = ymax !== null ? ymax : 0;
           }
         } else {
           this.ymax = parseInt(this.options.ymax, 10);
@@ -401,19 +404,24 @@
       } else {
         this.ymax = this.options.ymax;
       }
-      if (typeof this.options.ymin === 'string' && this.options.ymin.slice(0, 4) === 'auto') {
+      if (typeof this.options.ymin === 'string') {
-        if (this.options.ymin.length > 5) {
+        if (this.options.ymin.slice(0, 4) === 'auto') {
-          this.ymin = Math.min(parseInt(this.options.ymin.slice(5), 10), ymin);
+          if (this.options.ymin.length > 5) {
+            this.ymin = parseInt(this.options.ymin.slice(5), 10);
+            if (ymin !== null) {
+              this.ymin = Math.min(ymin, this.ymin);
+            }
+          } else {
+            this.ymin = ymin !== null ? ymin : 0;
+          }
         } else {
-          this.ymin = ymin;
+          this.ymin = parseInt(this.options.ymin, 10);
         }
-      } else if (typeof this.options.ymin === 'string') {
-        this.ymin = parseInt(this.options.ymin, 10);
       } else {
         this.ymin = this.options.ymin;
       }
       if (this.ymin === this.ymax) {
-        if (this.ymin !== 0) {
+        if (ymin) {
           this.ymin -= 1;
         }
         this.ymax += 1;

spec/lib/line/set_data_spec.coffee

@@ -38,6 +38,16 @@ describe 'Morris.Line data', ->
           ymax: 'auto'
         line.ymin.should.equal 10
         line.ymax.should.equal 15
+        line = Morris.Line
+          element: 'graph'
+          data: [{x: 1}, {x: 2}, {x: 3}, {x: 4}]
+          xkey: 'x'
+          ykeys: ['y', 'z']
+          labels: ['y', 'z']
+          ymin: 'auto'
+          ymax: 'auto'
+        line.ymin.should.equal 0
+        line.ymax.should.equal 1
 
     describe 'auto [n]', ->
 
@@ -48,10 +58,20 @@ describe 'Morris.Line data', ->
           xkey: 'x'
           ykeys: ['y', 'z']
           labels: ['y', 'z']
-          ymin: 'auto 12'
+          ymin: 'auto 11'
-          ymax: 'auto 12'
+          ymax: 'auto 13'
         line.ymin.should.equal 10
         line.ymax.should.equal 15
+        line = Morris.Line
+          element: 'graph'
+          data: [{x: 1}, {x: 2}, {x: 3}, {x: 4}]
+          xkey: 'x'
+          ykeys: ['y', 'z']
+          labels: ['y', 'z']
+          ymin: 'auto 11'
+          ymax: 'auto 13'
+        line.ymin.should.equal 11
+        line.ymax.should.equal 13
 
       it 'should use a user-specified minimum and maximum value', ->
         line = Morris.Line
@@ -64,4 +84,14 @@ describe 'Morris.Line data', ->
           ymax: 'auto 20'
         line.ymin.should.equal 5
         line.ymax.should.equal 20
+        line = Morris.Line
+          element: 'graph'
+          data: [{x: 1}, {x: 2}, {x: 3}, {x: 4}]
+          xkey: 'x'
+          ykeys: ['y', 'z']
+          labels: ['y', 'z']
+          ymin: 'auto 5'
+          ymax: 'auto 20'
+        line.ymin.should.equal 5
+        line.ymax.should.equal 20