Submit form thru javascript -

How do I submit a form when choosing a date? Trying to call it on the field change but not working, maybe I have to do this in the javascript section.

I have it

  & lt; Script type = "text / javascript" & gt; Calendar. Setup ({inputField: "element_4_3", basefield: "element_4", displayArea: "calendar_4", button: "cal_img_4", ifFormat: "% e% B,% Y", select: selectDate}); & Lt; / Script & gt;  

  & lt; Span id = "calendar_4" & gt; Data Aspirati: & lt; Img id = "cal_img_4" class = "datepicker" src = "images / calendar.gif" alt = "Select a date." OnChange = "this.form.submit ();" & Gt; & Lt; / Span & gt;  

How can I do this? Thanks