factorial.clj

(defn factorial [n]
  (if (= n 1)
    n
    (* n (factorial (dec n))))

(print (factorial 7))

factorial.js

function f(n) {
  var j = 1;
  for(var i = n; i > 0; i--) {
    j *= i
  }

  return j
}

console.log(f(7)) // 5040

factorial.rb

def factorial(n)
  return n if n == 1
  n * factorial(n - 1)
end

puts factorial(7)