Comment wording changes. Added default string stroke patterns object …

…to allow for more code reuse.

dygraph-canvas.js

@@ -840,15 +840,10 @@ DygraphCanvasRenderer.prototype._renderLineChart = function() {
     prevY = null;
     var drawPoints = this.dygraph_.attr_("drawPoints", setName);
     var strokePattern = this.dygraph_.attr_("strokePattern", setName);
-    if (strokePattern === 'solid') {
-      strokePattern = null;
-    } else if (strokePattern === 'dashed') {
-      strokePattern = [7, 3];
-    } else if (strokePattern === 'dotted') {
-      strokePattern = [2, 2];
-    } else if (strokePattern === 'dashdotted') {
-      strokePattern = [7, 2, 2, 2];
-    } else if (strokePattern && !strokePattern.length) {
+    if (typeof(strokePattern) === "string") {
+     // replace string with array pattern
+     strokePattern = Dygraph.DEFAULT_STROKE_PATTERNS[strokePattern];
+    } else if (!Dygraph.isArrayLike(strokePattern)) {
       strokePattern = null;
     }
     for (j = firstIndexInSet; j < afterLastIndexInSet; j++) {

dygraph-utils.js

@@ -35,6 +35,17 @@ Dygraph.ERROR = 3;
 // https://github.com/eriwen/javascript-stacktrace
 Dygraph.LOG_STACK_TRACES = false;
 
+/**
+ * The stroke patterns arrays for the string stroke patterns.
+ * @private
+ */
+Dygraph.DEFAULT_STROKE_PATTERNS = {
+    solid: null,
+    dashed: [7,3],
+    dotted: [2, 2],
+    dashdotted: [7, 2, 2, 2]
+};
+
 /**
  * @private
  * Log an error on the JS console at the given severity.
@@ -777,11 +788,11 @@ Dygraph.isPixelChangingOptionList = function(labels, attrs) {
 };
 
 /**
- * Compares two arrays to see if they are equal. If any of the parameters are
- * not arrays it will return false.
- * @param array1 First array
+ * Compares two arrays to see if they are equal. If either parameter is not an
+ * array it will return false.
+ * @param array1 first array
  * @param array2 second array
- * @return True if all parameters are arrays and contents are equal.
+ * @return True if both parameters are arrays, and contents are equal.
  */
 Dygraph.compareArrays = function(array1, array2) {
   if (!Dygraph.isArrayLike(array1) || !Dygraph.isArrayLike(array2)) {