Upload.jsx

onDrop(files,e) {
        let element;
        if (e.target.className.indexOf('box_gif') == -1) {
            element = e.target.parentElement;
            
        } else {
            element = e.target;
        }
        
        element.style.backgroundImage   = 'url('+files[0].preview+')';
        element.style.backgroundSize    = 'cover';
        element.className               = element.className + ' loading';

        let data = new FormData();

        files.forEach((k,v) => {
            data.append(k,v);
        });
        // * Create upload request
        let req = ajax.post('/upload');
        // * Attach images to request, to set proper header
        files.forEach((file) => {
            req.attach(file.name,file);
        });
        req.send({ id: 12333 })
        // * Process response
        req.end((err,res) => {
            var reg = new RegExp('(\\s|^)loading(\\s|$)')
            element.className=element.className.replace(reg, ' ');
            if (err || !res.ok)
                console.error(err);
        });
    }