title: Adding callback parameter to $.ajax with jsonp
body: <p>I am trying to implement jQuery ajax call for cross domain call using jsonp, and the code is like -</p>
  
  <pre><code>$.ajax({
      async:true,
      cached:true,
      url: 'cfcs/TempRepository.cfc?method=getAllCategories'
          +'&amp;storeID='+ storeId
          +'&amp;callback=?',
      type: 'get',
      data: '',
      dataType: 'jsonp',
      success: PopulateCategoryObject,
      error: function (xhr, status, error) {
          console.log(xhr + ',' + status + ',' + error);
      }
  });
  
  function PopulateCategoryObject(results) {
      //populate the categories
  }
  </code></pre>
  
  <p>I am confused here with the use of callback. 
  If I remove success attribute of $.ajax and use callback=PopulateCategoryObject in place of callback=? like -</p>
  
  <pre><code>$.ajax({
      async:true,
      cached:true,
      url: 'cfcs/TempRepository.cfc?method=getAllCategories'
          +'&amp;storeID='+ storeId
          +'&amp;callback=PopulateCategoryObject',
      type: 'get',
      data: '',
      dataType: 'jsonp',
      error: function (xhr, status, error) {
          console.log(xhr + ',' + status + ',' + error);
      }
  }); 
  </code></pre>
  
  <p>the difference it makes is, it returns result like -</p>
  
  <pre><code>PopulateCategoryObject, jQuery172012112959187034678_1376976441013( // data here )
  </code></pre>
  
  <p>And, the function PopulateCategoryObject is not executed.</p>
  
  <p>I am unable to figure it out how to set the callback function here? and why is "jQuery172012112959187034678_1376976441013" getting added here with the result?</p>
  
  <p>Thanks In Advance.</p>