using jquery I need to retrieve an array from table cells, format the data and pass it into a js function.

the code i am using is this:

 var l1 = new Array();
   $('table#datatable tbody td:first-child').each(function() {
   l1.push($(this).text());
   });

this is the table fragment

  <tr>
               <th scope="row">Age: 0-4</th>
               <td>0</td>
               <td>9.7</td>
           </tr>
           <tr>
               <th scope="row">5-17</th>
               <td>23.6</td>
               <td>18.0</td>
           </tr>
           <tr>
               <th scope="row">Total 0-17</th>
               <td>20.6</td>
               <td>16.1</td>
           </tr>

the table's id is "datatable". i want to return an array of the contents of each first td and then format it like this: 0,23.6,20.6

i am very new to using arrays...