letvsvar.js

#!/usr/bin/env node

(function(){
   function aFunction(){
      var a = "A1";
      let b = "B1";

      console.log(`Inside function, BEFORE variable assignments in "inner" lexical scope:\n\t<a: ${a}, b: ${b}>`);
      // Prints:
      // Inside function, BEFORE variable assignments in "inner" lexical scope:
      //    <a: A1, b: B1>

      {
         var a = "A2";
         let b = "B2";

         console.log(`Inside "inner" lexical scope:\n\t<a: ${a}, b: ${b}>`);
         // Prints:
         // Inside "inner" lexical scope:
	 //    <a: A2, b: B2>
      }

      console.log(`Inside function, AFTER variable assignments in "inner" lexical scope:\n\t<a: ${a}, b: ${b}>`);
      // Prints:
      // Inside function, AFTER variable assignments in "inner" lexical scope:
      //    <a: A2, b: B1>
   }

   aFunction();
})()