added bit_manipulation folder & binary_count_setbits.js file

Bit-Manipulation/binary_count_setbits.js

@@ -0,0 +1,20 @@
+/*
+    author: vivek9patel
+    license: GPL-3.0 or later
+
+    This script will find number of 1's
+    in binary representain of given number
+
+*/
+
+function binary_count_setbits(a) {
+  "use strict"
+  // convert number into binary representation
+  let binA = a.toString(2)
+
+  // return number of set bits in binary representaion
+  return binA.split("1").length - 1
+}
+
+// Run `binary_and` Function to find the binary and operation
+console.log(binary_count_setbits(251))