How to send an image to the server emulating FormData?

Question

JavaScript

The problem is the following - I need to send a picture via I wanted to send it in base64 format via FileReader(), but the server accepts it in binary format (maybe?). How can I emulate data in the same format that FormData creates?<input type="file">

// так отправляется запрос с через FormData.
data.append('windows_view', form.windows_view.value);
            data.append('preview_image', form.preview_image.files[0]);
            
            console.log('data: ', data);

            axios.post('/panel/apartment/create', data, {
                headers: {
                    'Accept': 'application/json',
                    'Accept-Language': 'en-US,en;q=0.8',
                    'Content-Type': `multipart/form-data`,
                }
            })

and so strangely shows the data that is sent via FormData, shows that it is binary. And now I need to make the same format through the FileReader so that the server skips it. How to do it?