title: javascript sum array values in multidimensional array with conditions
body: <p>I'm trying to use javascript to iterate over an object and sum the values of a property grouping by the value of another property.  Here is my example data that I am iterating over:</p>
  
  <pre><code>63.450,     2013-01-01 00:00:00,    63.450,     2013,   Amex Residuals
  3.980,      2013-01-01 00:00:00,    3.980,      2013,   Gift Cards on Demand
  -16.000,    2013-01-01 00:00:00,    -16.000,    2013,   Month End Fee Rejects
  67.140,     2013-02-01 00:00:00,    67.140,     2013,   Amex Residuals
  -600.000,   2013-02-01 00:00:00,    -600.000,   2013,   Bonus Take Back - Closed Less Than 6 Months
  -400.000,   2013-02-01 00:00:00,    -400.000,   2013,   Bonus Take Back - Did Not Activate
  8.910,      2013-02-01 00:00:00,    8.910,      2013,   Checks On Demand
  13997.770,  2013-02-01 00:00:00,    13997.770,  2013,   Global Report
  -15.000,    2013-02-01 00:00:00,    -15.000,    2013,   Merchant Adjustments
  -34.500,    2013-02-01 00:00:00,    -34.500,    2013,   Month End Fee Rejects
  </code></pre>
  
  <p>The data continues to include other months (through october) in the second column.  I need to sum all the values in the first column together for each distinct month, as well as create a javascript date from the 4th column year, so the result should be something like this:</p>
  
  <pre><code>var data = [ [Date.UTC('2013', i, 1), parseFloat('51.43')], [Date.UTC('2013', i, 1), parseFloat(13024.32)] ]; 
  </code></pre>
  
  <p>Essentially I should end up with a 2 element array for each month total tupled with a date object from the 4th column.  I'm just not sure how to do the iterations for summing on the conditional grouping of the 2nd column (date).</p>