title: problem setting up multidimensional array and using .push()
body: <p>I'm trying to setup a multidimensional array where I can push value into it where it needs to.</p>
  
  <p>For example, I have a <code>cacheArray = new Array(col0Array, col1Array, col2Array);</code> which would accessible using <code>cacheArray[0]</code> etc...</p>
  
  <p>Now, in a loop I would check <code>cacheArray[column_number].length</code>, which would be the length of whichever <code>colArray</code>. Depending on that I want to <code>cacheArray[column_number].push("my_class");</code></p>
  
  <p>My intention is to add the css class name to the sub column arrays, and check the previous value in the sub array for that column so I can get a checkered colour effect. But pushing like I did gives me an error: <code>cacheArray[column_number].push</code> is not a function.</p>
  
  <p>Any ideas on how to approach this problem?</p>