error on zero width/height

diff --git a/dygraph.js b/dygraph.js
index 6e72efe..077a329 100644 (file)
--- a/dygraph.js
+++ b/dygraph.js
@@ -186,13 +186,19 @@ Dygraph.prototype.__init__ = function(div, file, attrs) {
   // The div might have been specified as percent of the current window size,
   // convert that to an appropriate number of pixels.
   if (div.style.width.indexOf("%") == div.style.width.length - 1) {
-    // Minus ten pixels  keeps scrollbars from showing up for a 100% width div.
     this.width_ = div.offsetWidth;
   }
   if (div.style.height.indexOf("%") == div.style.height.length - 1) {
     this.height_ = div.offsetHeight;
   }
 
+  if (this.width_ == 0) {
+    this.error("dygraph has zero width. Please specify a width in pixels.");
+  }
+  if (this.height_ == 0) {
+    this.error("dygraph has zero height. Please specify a height in pixels.");
+  }
+
   // TODO(danvk): set fillGraph to be part of attrs_ here, not user_attrs_.
   if (attrs['stackedGraph']) {
     attrs['fillGraph'] = true;