1    var postData = new FormData($("#modal_form_id")[0]);
2
3                         $.ajax({
4                                 type:'POST',
5                                 url:'your-post-url',
6                                 processData: false,
7                                 contentType: false,
8                                 data : postData,
9                                 success:function(data){
10                                   console.log("File Uploaded");
11                                 }
12
13                              });
14

1 <form enctype="multipart/form-data" id="modal_form_id"  method="POST" >
2    <input type="file" name="documents">
3 </form>
4