Add binary search.

src/algorithms/search/binary-search/binarySearch.js

@@ -0,0 +1,35 @@
+import Comparator from '../../../utils/comparator/Comparator';
+
+/**
+ * @param {*[]} sortedArray
+ * @param {*} seekElement
+ * @param {function(a, b)} [comparatorCallback]
+ * @return {number}
+ */
+
+export default function binarySearch(sortedArray, seekElement, comparatorCallback) {
+  const comparator = new Comparator(comparatorCallback);
+
+  let startIndex = 0;
+  let endIndex = sortedArray.length - 1;
+
+  while (startIndex <= endIndex) {
+    const middleIndex = startIndex + Math.floor((endIndex - startIndex) / 2);
+
+    // If we've found the element just return its position.
+    if (comparator.equal(sortedArray[middleIndex], seekElement)) {
+      return middleIndex;
+    }
+
+    // Decide which half to choose for seeking next: left or right one.
+    if (comparator.lessThen(sortedArray[middleIndex], seekElement)) {
+      // Go to the right half of the array.
+      startIndex = middleIndex + 1;
+    } else {
+      // Go to the left half of the array.
+      endIndex = middleIndex - 1;
+    }
+  }
+
+  return -1;
+}