title: How to use array as key in Javascript?
body: <p>I have a simple example on python:</p>
  
  <pre><code>programs = {}
  if not programs.has_key(( program, time )):
       programs[( program, time )] = 0
  programs[( program, time )] = programs[( program, time )] + 1
  </code></pre>
  
  <p>How to use array as key in Javascript ?</p>