Added Interpolation and exponential searches in the javascript repo

Search/InterpolationSearch.js

@@ -0,0 +1,49 @@
+/*
+ * Interpolation Search
+ *  
+ * Time Complexity:
+ * -Best case: O(1)
+ * -Worst case: O(n)
+ * -O((log(log(n))) If the data are uniformly distributed
+ *
+ *  
+ */
+
+function interpolationSearch(arr, key) {
+
+    let length = arr.length - 1;
+    let low = 0;
+    let high = length;
+    let position = -1;
+    let delta = -1;
+
+    //Because the array is sorted the key must be between low and high
+    while (low <= high && key >= arr[low] && key <= arr[high]) {
+
+        delta = (key - arr[low]) / (arr[high] - arr[low]);
+        position = low + Math.floor((high - low) * delta);
+
+        //Target found return its position
+        if (arr[position] === key) {
+            return position;
+        }
+
+        //If the key is larger then it is in the upper part of the array
+        if (arr[position] < key) {
+            low = position + 1;
+            //If the key is smaller then it is in the lower part of the array    
+        } else {
+            high = position - 1;
+        }
+    }
+
+    return -1;
+}
+
+
+let arr = [2, 6, 8, 10, 12, 14, 16, 18, 20, 22, 26, 34, 39];
+
+console.log("Found at position :" + interpolationSearch(arr, 2));
+console.log("Found at position :" + interpolationSearch(arr, 12));
+console.log("Found at position :" + interpolationSearch(arr, 1000));
+console.log("Found at position :" + interpolationSearch(arr, 39));