helper math functions in javascript

my_math.js

// fixes that 2.55 is rounded to 2.5 and not 2.6 as it should have been
export function round(num, digits) {
  digits = isNaN(digits) ? 2 : digits;
  return +(Math.round(num + "e+" + digits)  + "e-" + digits).toFixed(digits);
}