title: Are Javascript arrays sparse?
body: <p>That is, if I use the current time as an index into the array:</p>
  
  <pre><code>array[Date.getTime()] = value;
  </code></pre>
  
  <p>will the interpreter instantiate all the elements from 0 to now?  Do different browsers do it differently?</p>
  
  <p>I remember there used to be a bug in the <a href="http://www-03.ibm.com/systems/power/software/aix/" rel="noreferrer">AIX</a> kernel, which would create pseudo-ttys on request, but if you did, say, "echo > /dev/pty10000000000" it would create /dev/pty0, /dev/pty1, .... and then fall over dead.  It was fun at trade shows, but I don't want this to happen to my customers.</p>