title: How does jsPerf determine which of the code snippets is fastest?
body: <p>Today I visited <a href="http://jsperf.com/" rel="nofollow noreferrer">jsPerf</a> and now I am wondering…</p>
  <ol>
  <li>What is &quot;ops/sec&quot;?</li>
  <li>How many iterations does it do?</li>
  <li>On what basis does it calculate which is faster? What is the formula behind these calculations?</li>
  </ol>
  <p>Example: <a href="http://jsperf.com/concatenation-vs-join" rel="nofollow noreferrer">http://jsperf.com/concatenation-vs-join</a></p>
  <p>Can anyone tell me?</p>