Send selected checkbox' s value with AJAX

i have many checkbox like this

<table>
  <tr><td>data1</td><td><input type='checkbox' name='cek[]' /></td></tr>
  <tr><td>data2</td><td><input type='checkbox' name='cek[]' /></td></tr>
  <tr><td>data3</td><td><input type='checkbox' name='cek[]' /></td></tr>
  <tr><td>data4</td><td><input type='checkbox' name='cek[]' /></td></tr>
</table>

how to write the javascript and AJAX code to send the value which one i check? when i check the data2's checkbox, the database about data2 should be change..