I'm trying to do the following :
- First, a textBox get the focus on page load (no problem here) 
- Then, when - ENTERbutton is pressed inside that textBox, it switch focus to the second textBox.
- Finally, when - ENTERis pressed in that second textBox, it does a postback and reahes code behind event just like when you press a classic- <asp:button />
Based on :
Fire event on enter key press for a textbox
and
JavaScript set focus to HTML form element
I managed to come up with :
HTML :
 <asp:TextBox ID="txtNNoSerie" runat="server"  Width="150px" ClientIDMode="Static" onkeypress="EnterEventFirst(event)" AutoPostBack="false"></asp:TextBox>             
 <asp:TextBox ID="txtNNoIdentification" runat="server" Width="150px" ClientIDMode="Static" onkeypress="EnterEventSecond(event)" AutoPostBack="false"></asp:TextBox>
 <asp:Button id="btnAjouter" CssClass="ms-Button ms-Button--primary" onclick="btnAjouter_click" Text="+" ForeColor="White" runat="server"  Width="30px" />
    <input type="text" id="txtTest" /> <%-- Just for tests --%>
JS :
  function EnterEventFirst(e) {
      if (e.keyCode == 13) {
          document.getElementById('txtTest').value = 'got it';
          document.getElementById('<%=txtNNoIdentification.ClientID%>').focus();
      }
  } 
  function EnterEventSecond(e) {
      if (e.keyCode == 13) {
          document.getElementById('txtTest').value = 'Again';
          __doPostBack('<%=btnAjouter.ClientID%>', "");
      }
  }
Code behind :
    protected void btnAjouter_click(object sender, EventArgs e)
    {
    }
JavaScript functions are reached, because i can see "got it" and "Again" in the test TextBox, but just for half a second and then it desapear... The __DoPostBack funtion does not work.
Looks like when you press enter in a textBox, it automaticaly does a useless postback and page reload... And that is where i'm stuck
 
     
    