HTML5 FormData文件上传

<form id= "form">  
              <div >文件名： <input type="text" name="filename" value= ""/></div >  
              <div >上传文件： <input type="file" name="file"/></div>  
              <button onclick="uploadFileAction()" >上传</button>  
</form>
<script class="lazyload" src="data:image/png;base64,iVBORw0KGgoAAAANSUhEUgAAAAEAAAABCAYAAAAfFcSJAAAAAXNSR0IArs4c6QAAAARnQU1BAACxjwv8YQUAAAAJcEhZcwAADsQAAA7EAZUrDhsAAAANSURBVBhXYzh8+PB/AAffA0nNPuCLAAAAAElFTkSuQmCC" data-original="http://libs.baidu.com/jquery/2.0.0/jquery.min.js"></script>
        <script>
            function uploadFileAction() {  
                 var formData = new FormData($( "#form" )[0]); //重点     
                 $.ajax({  
                      url: url ,  
                      type: 'POST',  
                      data: formData,  
                      async: false,  
                      cache: false,  
                      contentType: false,  
                      processData: false,  
                      success: function (resp) {  
                          console.log(resp);  
                      },  
                      error: function (error) {  
                          console.log(error);  
                      }  
                 });  
            }  
        </script>