jQuery.ajax() not firing

I used Firebug to debug my code. In the "Net" panel, I don't see the .ajax() firing at all. (didn't see any outgoing request url)

What is wrong with my code?

Edited: After i added $(document).ready(). to my co开发者_如何学Cde, everything just works fine. Why do I need $(document).ready() ? I thought when the button is clicked, the document is ready for sure. Needed to add "return false;" as well

function doSubmit() {
        alert('button is clicked.');

        $.ajax({
          type: 'Post',
          url: "http://mysite.com/list/json",
          dataType: "json",
          context: [],
          success: function(data){
              alert('got data');
          }
        }); 
}       

<form name="my_form" id="myform">
    <div class="mydiv">
        <input class="button" type="submit" value="Save" onClick="doSubmit();">
    </div>
</form>

You have to return false, otherwise it just submits that form

function doSubmit() {
        alert('button is clicked.');

        $.ajax({
          type: 'Post',
          url: "http://mysite.com/list/json",
          dataType: "json",
          context: [],
          success: function(data){
              alert('got data');
          }
        }); 
       return false;
}       

$('#myform').submit(function() {
    $.ajax({
        // ...
    });
});