formdata js

1var form = $('form')[0]; // You need to use standard javascript object here
2var formData = new FormData(form);
3
4or specify exact data for FormData();
5
6var formData = new FormData();
7formData.append('section', 'general');
8formData.append('action', 'previewImg');
9// Attach file
10formData.append('image', $('input[type=file]')[0].files[0]); 
11
12Sending form
13
14Ajax request with jquery will looks like this:
15
16$.ajax({
17    url: 'Your url here',
18    data: formData,
19    type: 'POST',
20    contentType: false, // NEEDED, DON'T OMIT THIS (requires jQuery 1.6+)
21    processData: false, // NEEDED, DON'T OMIT THIS
22    // ... Other options like success and etc
23});
24After this it will send ajax request like you submit regular form
25with enctype="multipart/form-data"
26
27Update: This request cannot work without type:"POST" in options since all
28files must be sent via POST request.

1var formData = new FormData();
2fromData.append('name','value');