add js solution for 191

Author: limbowandering

solution/191. Number of 1 Bits/Solution.js

@@ -0,0 +1,8 @@
+const hammingWeight = function(n){
+  let result = 0;
+  while(n){
+    result += n & 1;
+    n = n >>> 1;
+  }
+  return result;
+}