title: jQuery + Ajax: submit a single textbox to a controller
body: <p>I'm working on a timesheet application. I'd like to add an autosave functionality.
  Let's say I have a form like this:</p>
  
  <pre><code>&lt;form id="timesheet" action="save_timesheet.html" method="POST"&gt;
  &lt;input type="text" id="day1taskid2" /&gt;
  &lt;input type="text" id="day2taskid2" /&gt;
  &lt;input type="text" id="day3taskid2" /&gt;
  &lt;input type="text" id="day41taskid2" /&gt;
  ...
  &lt;/form&gt;
  </code></pre>
  
  <p>If a user inserts a new value (= <code>onChange</code>) I'd like to get that specific value and send it to my controller (using JSON/Ajax). For example: I add 2 hours to a specific textbox, and the jQuery ajax should do the update <code>onChange</code>. It's pretty hard to find a working example. I've seen a lot of examples using a form, but I'm not submitting the whole form, only one small textbox. There can be over 70 textboxes on one screen, depending on the amount of tasks to show.</p>
  
  <p>What do I need? Could you give me an easy-to-understand example for this case? I'm using Spring 2.x.</p>
  
  <p><strong>Added the solution ;-)</strong></p>