title: Why does this index of a two dimensional array return -1
body: <p>I have the following code:</p>
  
  <pre><code>alert( [[0,1],[1,0]].indexOf([0,1]) );
  </code></pre>
  
  <p>And even though the array [0,1] is an element of the two-dimensional array, I get a value of '-1' returned. What have I done wrong in life?</p>