JS-Score Reference Implementation

jsscore.js

/**
 * Compute a jsscore for the current JS environment
 *
 * @param n (Number) Number of iterations to run.  For best results this value
 *                   should be selected such that the run time is between 0.1 and
 *                   0.5 seconds.  The default (1,000,000) will fall well short of
 *                   this on modern devices.  This is by design so as to prevent
 *                   unintentional CPU contention, but will likely yield inaccurate
 *                   results.
 *
 * @returns (Number) The JS-Score
 */
function jsscore(n) {
  n = n || 1e6;                                 // Default is to count to 1,000,000

  var t = new Date().getTime();                 // Start timer
  for (var i = 0; i < n; i++);                  // Loop
  t = new Date().getTime() - t;                 // Stop timer

  return Math.log(n / t * 1000) / Math.log(10); // Return log10(iterations/second)
}