--- /dev/null	Thu Jan 01 00:00:00 1970 +0000
+++ b/toolkit/javascript/d3/src/core/extent.js	Thu Apr 10 14:20:23 2014 +0200
@@ -0,0 +1,21 @@
+d3.extent = function(array, f) {
+  var i = -1,
+      n = array.length,
+      a,
+      b,
+      c;
+  if (arguments.length === 1) {
+    while (++i < n && ((a = c = array[i]) == null || a != a)) a = c = undefined;
+    while (++i < n) if ((b = array[i]) != null) {
+      if (a > b) a = b;
+      if (c < b) c = b;
+    }
+  } else {
+    while (++i < n && ((a = c = f.call(array, array[i], i)) == null || a != a)) a = undefined;
+    while (++i < n) if ((b = f.call(array, array[i], i)) != null) {
+      if (a > b) a = b;
+      if (c < b) c = b;
+    }
+  }
+  return [a, c];
+};