Run results for: Find prime gaps - with or without intermediate var

Run details:

User agent: Mozilla/5.0 (Windows NT 10.0; Win64; x64) AppleWebKit/537.36 (KHTML, like Gecko) Chrome/120.0.0.0 Safari/537.36 Edg/120.0.0.0

Browser: Chrome 120

Operating system: Windows

Device Platform: Desktop

Date tested: 2 years ago

Test name	Executions per second
Use intermediate var	1.8 Ops/sec
Use repeated calculation	1.7 Ops/sec

Script Preparation code:

var fromNum = 2,
    toNum = 1000000;
function isPrime(n) {
  for (var i = 2; i*i <= n; i++) {
    if ((n/i)%1 == 0) {
      return false;
    }
  }
  return true;
}
function primeGaps(start, end) {
  if (start < 1) {throw ''}
  result = {};
  var currentPrime = null;
  var primeGap = null;
  for (var i = start; i <= end; i++) {
    if (isPrime(i)) {
      if (currentPrime !== null) {
        primeGap = i - currentPrime;
        if (!result.hasOwnProperty(primeGap)) {
          result[primeGap] = currentPrime;
        }
      }
      currentPrime = i;
    }
  }
  return result;
}
function primeGapsAlt(start, end) {
  if (start < 1) {throw ''}
  result = {};
  var currentPrime = null;
  for (var i = start; i <= end; i++) {
    if (isPrime(i)) {
      if (currentPrime !== null) {
        if (!result.hasOwnProperty(i - currentPrime)) {
          result[i - currentPrime] = currentPrime;
        }
      }
      currentPrime = i;
    }
  }
  return result;
}

Tests:

Use intermediate var
primeGaps(fromNum, toNum);
Use repeated calculation
primeGapsAlt(fromNum, toNum);

Run results for: Find prime gaps - with or without intermediate var

Use intermediate var

Use repeated calculation