Why does [5,6,8,7][1,2] = 8 in Javascript
<p>I can't wrap my mind around this quirk.</p>

<pre><code>[1,2,3,4,5,6][1,2,3]; // 4
[1,2,3,4,5,6][1,2]; // 3
</code></pre>

<p>I know <code>[1,2,3] + [1,2] = 1,2,31,2</code>, but I can't find what type or operation is being performed.</p>
