Complete "longest common ..." examples (#100)

* no else return

* fix var ref

* fix importing/requiring dependencies

* complete longest common examples

03_recursion/javascript/01_countdown.js

@@ -3,9 +3,9 @@ function countdown(i) {
   // base case
   if (i <= 0) {
     return;
-  } else {
-    countdown(i-1);
   }
+
+  countdown(i - 1);
 }
 
 countdown(5);

03_recursion/javascript/03_factorial.js

@@ -1,9 +1,8 @@
 function fact(x) {
   if (x === 1) {
     return 1;
-  } else {
-    return x * fact(x-1);
   }
+  return x * fact(x - 1);
 }
 
 console.log(fact(5));