From: Eugene Crosser <crosser@average.org>
Date: Thu, 4 Feb 2016 21:49:53 +0000 (+0300)
Subject: don't draw plot w/o data
X-Git-Url: http://www.average.org/gitweb/?p=pulsecounter.git;a=commitdiff_plain;h=02a022b2e79351dd4008240dfcd8ab081a8ba186;hp=2a268273df281b5a4fa5fcd29c29042877deace0

don't draw plot w/o data
---

diff --git a/web/index.html b/web/index.html
index 9181b79..7c0b4a4 100644
--- a/web/index.html
+++ b/web/index.html
@@ -193,14 +193,16 @@
   function drawplot(data, color) {
     var i;
 
-    ctx.beginPath();
-    ctx.moveTo(px(data[0][0]), py(data[0][1]));
-    for (i = 1; i < data.length; i++) {
-      ctx.lineTo(px(data[i][0]), py(data[i - 1][1]));
-      ctx.lineTo(px(data[i][0]), py(data[i][1]));
+    if (data.length) {
+      ctx.beginPath();
+      ctx.moveTo(px(data[0][0]), py(data[0][1]));
+      for (i = 1; i < data.length; i++) {
+        ctx.lineTo(px(data[i][0]), py(data[i - 1][1]));
+        ctx.lineTo(px(data[i][0]), py(data[i][1]));
+      }
+      ctx.strokeStyle = color;
+      ctx.stroke();
     }
-    ctx.strokeStyle = color;
-    ctx.stroke();
   }
 
   function showloading() {