提交时切换按钮

How do i switch one button off and another on, onsubmit. Just like when someone sends a friend request to another on facebook. When the user click on send friend request, the button then changes to friend request sent. here's my html. how do i do that with jquery or ajax

<tr>
          <td bgcolor="#eaeaea"><div align="center" id="send_msg">
            <input type="submit" name="button3" id="button3" value="Send Message" />
          </div></td>
          <td bgcolor="#eaeaea"><div id="msg_sent">
            <input type="submit" name="button2" id="button2" value="Message Sent" />
          </div></td>
        </tr>

You can catch "submit" event in the forms events (need a bit of JS, also possible with JQuery).

See this: http://www.w3schools.com/jsref/event_form_onsubmit.asp

In your onsubmit JS function you'd typically change object properties that need to be changed (hide buttons, enable/disable etc.)

It is, however, possibly better to include one DIV (with ID) where you can show status (e.g. "message has been sent") and enable/disable send button, but that is rather a matter of your design decisions.

I think you mean that after the form submit,you need to change the value of the button.If it is like this,you can do the ajax stuff for sending the message and do like this

<tr>
      <td bgcolor="#eaeaea"><div align="center" id="send_msg">
        <input type="submit" name="button3" id="button3" value="Send Message" />
</tr>

jquery:

$("#button3").click(function(){
    $.(ajax)({
              ..........

     }).done(function(){
    $("#button3").val("Message sent");
  });

});

This will change the button text of send message button and you actually require only one button