Fixed and simplified binary search

lib/util.js

@@ -1155,62 +1155,31 @@ exports.mergeOptions = function (mergeTarget, options, option) {
  * @private
  */
 exports.binarySearch = function(orderedItems, range, field, field2) {
-  var array = orderedItems;
-
   var maxIterations = 10000;
   var iteration = 0;
-  var found = false;
   var low = 0;
-  var high = array.length;
-  var newLow = low;
-  var newHigh = high;
-  var guess = Math.floor(0.5*(high+low));
-  var value;
+  var high = orderedItems.length - 1;
 
-  if (high == 0) {
-    guess = -1;
-  }
-  else if (high == 1) {
-    if (array[guess].isVisible(range)) {
-      guess =  0;
-    }
-    else {
-      guess = -1;
-    }
-  }
-  else {
-    high -= 1;
+  while (low <= high && iteration < maxIterations) {
+    var middle = Math.floor((low + high) / 2);
 
-    while (found == false && iteration < maxIterations) {
-      value = field2 === undefined ? array[guess][field] : array[guess][field][field2];
+    var item = orderedItems[middle];
+    if (item.isVisible(range)) { // jihaa, found a visible item!
+      return middle;
+    }
 
-      if (array[guess].isVisible(range)) {
-        found = true;
-      }
-      else {
-        if (value < range.start) { // it is too small --> increase low
-          newLow = Math.floor(0.5*(high+low));
-        }
-        else {  // it is too big --> decrease high
-          newHigh = Math.floor(0.5*(high+low));
-        }
-        // not in list;
-        if (low == newLow && high == newHigh) {
-          guess = -1;
-          found = true;
-        }
-        else {
-          high = newHigh; low = newLow;
-          guess = Math.floor(0.5*(high+low));
-        }
-      }
-      iteration++;
+    var value = (field2 === undefined) ? item[field] : item[field][field2];
+    if (value < range.start) {  // it is too small --> increase low
+      low = middle + 1;
     }
-    if (iteration >= maxIterations) {
-      console.log("BinarySearch too many iterations. Aborting.");
+    else {  // it is too big --> decrease high
+      high = middle - 1;
     }
+
+    iteration++;
   }
-  return guess;
+
+  return -1;
 };
 
 /**