title: Weird Behaviour when nesting 2D arrays in a 3D array
body: <p>Currently I'm working on a Minimax algorithm for four-in-a-row in javascript. I have decided to store possible moves in a array, continuing to nest arrays within arrays for every branch.</p>
  
  <p>However, when I attempt to edit a certain value in an array, it edits all other values within the same column. </p>
  
  <p>Code:</p>
  
  <pre><code>var BOARD = [
      [0, 0, 0],
      [0, 0, 0],
      [0, 0, 0]
      ];
  
  // Put 3 x 2D Arrays into one 3D Array
  var NODE_TREE = [BOARD, BOARD, BOARD];
  NODE_TREE[1][2][0] = 2;
  console.log(NODE_TREE);
  </code></pre>
  
  <p>Chrome V8 interpreter output: </p>
  
  <pre><code>[ [ [ 0, 0, 0 ], [ 0, 0, 0 ], [ 2, 0, 0 ] ],
    [ [ 0, 0, 0 ], [ 0, 0, 0 ], [ 2, 0, 0 ] ],
    [ [ 0, 0, 0 ], [ 0, 0, 0 ], [ 2, 0, 0 ] ] ]
  </code></pre>
  
  <p>What should happen but dosen't:</p>
  
  <pre><code>[ [ [ 0, 0, 0 ], [ 0, 0, 0 ], [ 0, 0, 0 ] ],
    [ [ 0, 0, 0 ], [ 0, 0, 0 ], [ 2, 0, 0 ] ],
    [ [ 0, 0, 0 ], [ 0, 0, 0 ], [ 0, 0, 0 ] ] ]
  </code></pre>
  
  <p>Javascript seems to ignore the First dimension index number. This issue only happens when I use an existing array nested within an array. If I were to make a 3D array from scratch, this bug does not happen.  </p>