functions javascript round numbers

round.js

function round(n, e) {
  const f = e === 0 ? 1 : Math.pow(10, e);
  return Math.round(n * f) / f;
}

// test examples
/*
> round(123.123, 2)
< 123.12
> round(123.123, 1)
< 123.1
> round(123.123, 0)
< 123
> round(123.123, 2)
< 123.12
> round(123.123, -2)
< 100
> round(123.123, -1)
< 120
*/