S3 presigned url

client.js

var React = require('react');
var Dropzone = require('react-dropzone');
var axios = require('axios');

exports = module.exports = React.createClass({
  _onDrop: function (files) {
    var file = files[0];

    axios.get(ENDPOINT_TO_GET_SIGNED_URL, {
      filename: file.name,
      filetype: file.type
    })
    .then(function (result) {
      var signedUrl = result.data.signedUrl;
      
      var options = {
        headers: {
          'Content-Type': file.type
        }
      };

      return axios.put(signedUrl, file, options);
    })
    .then(function (result) {
      console.log(result);
    })
    .catch(function (err) {
      console.log(err);
    });
  },
  render: function () {
    return (
      <Dropzone onDrop={ this._onDrop } size={ 150 }>
        <div>
          Drop some files here!
        </div>
      </Dropzone>
    );
  }
});

server.js

var aws = require('aws-sdk');

aws.config.update({
    accessKeyId: AWS_ACCESS_KEY
    secretAccessKey: AWS_SECRET_KEY
});

exports = module.exports = {
    sign: function(filename, filetype) {
        var s3 = new aws.S3();

        var params = {
            Bucket: SOME_BUCKET,
            Key: filename,
            Expires: 60,
            ContentType: filetype
        };

        s3.getSignedUrl(‘putObject’, params, function(err, data) {
            if (err) {
                console.log(err);
                return err;
            } else {
                return data;
            }
        });
    }
};