implemented binary search

Author: joynal

src/search/binary.js

@@ -0,0 +1,22 @@
+// A recursive binary search function. It returns true if target
+// is present in given array, otherwise return false
+const binarySearch = (arr, lo, hi, target) => {
+  // element is not present in array
+  if (lo > hi) return false;
+
+  const mid = Math.floor(hi + lo / 2);
+
+  // If the element is present at the middle
+  if (arr[mid] === target) return true;
+
+  // If element is smaller than mid, then
+  // it can only be present in left subarray
+  if (arr[mid] > target) {
+    return binarySearch(arr, lo, mid - 1, target);
+  }
+
+  // Else the element can only be present in right subarray
+  return binarySearch(arr, mid + 1, hi, target);
+};
+
+module.exports = (arr, target) => binarySearch(arr, 0, arr.length - 1, target);

tests/search/binary.test.js

@@ -0,0 +1,15 @@
+const binarySearch = require('../../src/search/binary');
+
+describe('binary search unit test:', () => {
+  it('Test#1 fail test', async () => {
+    const want = false;
+    const got = binarySearch([2, 3, 5, 6, 7, 9], 13);
+    expect(got).toBe(want);
+  });
+
+  it('Test#2 find a value', async () => {
+    const want = true;
+    const got = binarySearch([-7, -7, -3, 6, 17, 34, 42, 50, 52, 83, 87, 89, 96], 96);
+    expect(got).toBe(want);
+  });
+});