Upload file from the browser

rest.js

import immutable from 'immutable';
import request from 'superagent';
import userSession from './store/userSession';

const OAUTH_TOKEN = 'Authorization';

function doRequest(req, headers={}) {
    let token = userSession.store.current.get('access_token');
    if (token) {
        headers[OAUTH_TOKEN] = `Bearer ${token}`;
    }

    return new Promise((resolve, reject) => {
        if (headers !== undefined) {
            req = req.set(headers);
        }
        req.withCredentials().end((error, response) => {
            if (error || !response || !response.ok) {
                reject(error || new Error('Unspecified error'));
            } else if (!response.body && response.text) {
                reject(new Error('Response was not parsed as JSON; was Content-Type set to application/json?'));
            } else {
                resolve(immutable.fromJS(response.body));
            }
        });
    });
}

export function uploadFile(url, contentType, data) {
    return new Promise((resolve, reject) => {
      request.put(url)
        .send(data)
        .type(contentType)
        .end((error, response) => {
          if (error || !response || !response.ok) {
            reject(error || new Error('Unspecified error'));
          } else {
            resolve(url);
          }
        })
    })
}

export default {uploadFile};