JSFiddle - React, Tailwind, and code Playground

JavaScript

function fac(n)
{
    if(n===1 || n===0){
        return 1;
    } else {
        return n * fac(n-1);
    }
}

var test1 = (function(x) {
  return fac(x);
})(100);

var test2;
! function(x) {
  test2 = fac(x);
}(100);

console.log( test1 );
console.log( test2 );