Question

jQuery: How to enable beforeSend for $.ajax({dataType:'jsonp'...? Is there any solution?
http://jsfiddle.net/laukstein/2wcpU/

<div id="content"></div>
<script>
$.ajax({
    type:"GET",
    url:'http://lab.laukstein.com/ajax-seo/.json',
    dataType:'jsonp',
    async:false,
    beforeSend:function(data){ // Are not working with dataType:'jsonp'
      $('#content').html('Loading...');
    },
    success:function(data){
        $('#content').html(data.content);
    }
});
</script>

Answer 1

This is just the nature of how JSONP works, creating a <script> tag, not actually using a XMLHttpRequest to get data.
For what you’re doing, you can just run the code before, like this:

$('#content').html('Loading...');
$.ajax({
  type:"GET",
  url:'http://lab.laukstein.com/ajax-seo/.json',
  dataType:'jsonp',
  async:false,
  success:function(data){
    $('#content').html(data.content);
  }
});