title: Cannot set property '3' of undefined in 2 dimensional array
body: <p>I am trying to create a 2 dimensional array but am getting this error.</p>
  
  <p>I loop an object and try to assign them but it won't let me assign a value to the second dimension.</p>
  
  <p>This is what I have:</p>
  
  <pre><code>//this is globally set
  var gcollision = new Array();
  
  function create() {
      for (var X in sdata) {
          X = parseInt(X);
          for (var Y in sdata[X]) {
              Y = parseInt(Y);
              width = parseInt(sdata[X][Y][2]);
              height = parseInt(sdata[X][Y][3]);
              for (i = X; i != X + width; i++) {
                  //error occurs here "Uncaught TypeError: Cannot set property '3' of undefined"
                  gcollision[i][Y] = 1
                  for (j = Y; j != Y + height; j++) {
                      gcollision[X][j] = 1
                  }
              }
          }
      }
  </code></pre>
  
  <p>How do I make it set the value of properly?</p>
  
  <p>EDIT  sdata looks like this:</p>
  
  <pre><code>var sdata = {"4":{"7":["1","7","3","3"]},"3":{"3":["2","8","1","1"]}};
  </code></pre>