preventDefault（）打破了外部PHP的AJAX请求

Question

I wrote an AJAX request for uploading a file and add it's details to MySql database (by a form).

The code works great, but breaks when I add preventDefault() to the submit event (to not be directed to the external PHP file).

 $("#upload-form").submit(function(event){

            // TODO: check why breaks PHP code
            // event.preventDefault();

The same structure works great with other AJAX requests on the same file (for example AJAX request for editing MySql database).

I know the AJAX request is submitted because a new folder is created on my server (as part of the PHP code) but the file isn't uploaded.

I will be happy for an answer for one of these questions:

1. What preventDefault() doe's that can interfere otherwise working AJAX request?
2. How can I debug the external PHP code? as I'm not directed to it (because of the preventDefault())?

If my question is not clear enough - please help me make it clearer.

Answer 1

Since you are calling event.preventDefault() I am assuming you are sending form data with ajax.

If you want to upload files with ajax, you need to set processData: false and contentType: false on your ajax request.

See jQuery Ajax File Upload.