Round a number to 2 or more decimal places

I’m working in TypeScript. Is there an accepted way of rounding a number to n decimal places, or more, if the precision exists in the number?

The number must be represented as a string to avoid precision errors (e.g. 2.3 - 2 = 0.2999999999999998)

For example:

precision = [2, 6];

tx(0.000000, precision) => 0.00
tx(0.123123, precision) => 0.123123

tx(2.00, precision) => 2.00
tx(2, precision) => 2.00

tx(2.01, precision) => 2.01
tx(2.001, precision) => 2.001
tx(2.000000001, precision) => 2.00
tx(2.000001, precision) => 2.000001

I can use this to deal with funky epsilon errors while still allowing users to enter more precise numbers than a fixed DP.

>Solution :

Use toLocaleString with minimumFractionDigits and maximumFractionDigits parameters

function tx(value, [minimumFractionDigits, maximumFractionDigits]) {
  const result = value.toLocaleString('en-US', {
    minimumFractionDigits,
    maximumFractionDigits
  });
  
  console.log( {value, result} );
  return result;

}


const precision = [2, 6];

tx(0.000000, precision)
tx(0.123123, precision)

tx(2.00, precision)
tx(2, precision)

tx(2.01, precision)
tx(2.001, precision)
tx(2.000000001, precision)
tx(2.000001, precision)