const vs let when calling require

const can be normally used when you don’t want your program

1. to assign anything to the variable

   "use strict";
   const a = 1;
   a = 2;
   

   will produce TypeError: Assignment to constant variable..

2. to use the variable without explicitly initializing.

   "use strict";
   const a;
   

   will produce SyntaxError: Unexpected token ;

Simply put, I would say,

• use const whenever you want some variables not to be modified

• use let if you want the exact opposite of const

• use var, if you want to be compatible with ES5 implementations or if you want module/function level scope.

Use let only when you need block level scoping, otherwise using let or var would not make any difference.