uploading files to s3 using coffeescript

Question

I am trying to upload files using pre-signed url to s3 bucket. I am getting the pre-signed url by hitting a rest endpoint, which returns a json with the required details.

Now, I have to take this json and get the input file from user, to upload the file.

Here is the code, I have written in coffeescript. I am taking an input file obj from user and storing in file object and then calling the pre-signed api to get the json.

uploadFile: (e) =>
      files_container = e.target.form.elements[0].files
      if files_container.length > 0
        @file_obj = files_container[0]
        console.log(@file_obj)
        result = ""
        $.ajax
          type: 'GET'
          url: '/api/upload/get_lead_upload_url'
          dataType: "json"
          success: (response) ->
            console.log(response)

Below, I have to write this python code in coffeescript to upload the file.

with open(object_name, 'rb') as f:
    files = {'file': (object_name, f)}
    http_response = requests.post(response['url'], data=response['fields'], files=files)
# If successful, returns HTTP status code 204

Below is the part, where I am going wrong while creating the payload like the python code.

   formdata = new FormData
    formdata = response.fields
    formdata['file']= {@file_obj['name'], @file_obj}
    console.log(formdata)

The post request is giving me 403 forbidden error.

            $.ajax
              type:'POST'
              dataType: "jsonp"
              url: response.url
              headers: {'Access-Control-Allow-Origin': '*'}
              data: formdata
              success: (uploadResponse) -> 
                console.log(uploadResponse)

              error: (uploadResponse) -> 
                console.log('error')
                console.log(uploadResponse)

          error: (response) ->
            console.log('error')