4 numbers max variance calculation

Question

I have an array of four numbers, something like [597103978, 564784412, 590236070, 170889704] and I need to make sure that the variance is no more than 10%, for example for the array above, the check must fail because of the number 170889704.

Can someone suggest me a good method how to do that is Javascript?

Thanks in advance!

Answer 1

I would do it using Array.every

const arr = [597103978, 564784412, 590236070, 170889704];

const variance = (n, m) => {
  return Math.abs( (n - m) / n );
};

const isLessThanTenPercent = (n) => {
  return ( n < 0.1 );
};

const arrayIsGood = arr.every((n, i) => {

  // m is the next element after n
  const m = arr[i+1];
  if (Number.isInteger(m)) {
    const v = variance(n, m);
    return isLessThanTenPercent(v);
  } else {
    // if m is not an integer, we're at the last element
    return true;
  }

});

console.log({arrayIsGood});