Yes, you can use let within node.js, however you have to run node using the optional –harmony flag. Try the following test.js:
"use strict"
var x = 8,
y = 12;
{ let x = 5, y = 10; console.log(x + y); }
console.log(x + y);
And then run the file node --harmony test.js
which results in:
15
20
I would not recommend using this in an important production application, but the functionality is available now.