tail call optimization on fibonacci

fibTco.js

const fib = n => (n <= 2 ? 1 : fib(n - 1) + fib(n - 2));
const fibTco = (n, a = 1, b = 1) => (n === 1 ? a : fibTco(n - 1, b, a+b));

const nth = 42;

console.log(`fib(${nth}) =`);
console.log(` ${fib(nth)}`);
console.log(`fibTco(${nth}) = `);
console.log(` ${fibTco(nth)}`);

const tail = (n, a = 1) => {
  if (n <= 1) {
    return a;
  } else {
    return tail(n - 1, a + 1);
  }
}
console.log('But js does not have tail call optimization?')
console.log('tail(10000) = ')
console.log(tail(10000))