aws-uploader riot component with server side code

aws-uploader.html

const riot = require('riot')

<aws-uploader>
  <div class='container'>
    <form method="POST" action="/save-details">
      <input type="file" id="file-input" onchange={initUpload}>
	  <p id="status">Please select a file</p>
	  <section if={opts.imagefile === 'true'}>
		  <img style="border:1px solid gray;width:300px;"  id="preview" src="/images/default.png">
		  <input type="hidden" id="avatar-url" name="avatar-url" value="/images/default.png">
	  </section>
	  <button>Submit</button>
    </form>
  </div>
  <script type="es6">
    let self = this
    
    /*
      Function to carry out the actual PUT request to S3 using the signed request from the app.
    */
    self.uploadFile = (file, signedRequest, url) => {
    	const xhr = new XMLHttpRequest();
      xhr.open('PUT', signedRequest);
      xhr.onreadystatechange = () => {
        if(xhr.readyState === 4){
          if(xhr.status === 200){
          	if(self.opts.imagefile === 'true'){
	            self.root.querySelector('#preview').src = url;
	            self.root.querySelector('#avatar-url').value = url;
          	}
          	
          	self.parent.location_url = url
            self.parent.update()
          }
          else{
            alert('Could not upload file.');
          }
        }
      };
      xhr.send(file);
    }

    /*
      Function to get the temporary signed request from the app.
      If request successful, continue to upload the file using this signed
      request.
    */
    self.getSignedRequest = (file) => {
      const xhr = new XMLHttpRequest();
      xhr.open('GET', `/sign-s3?file-name=${file.name}&file-type=${file.type}`);
      xhr.onreadystatechange = () => {
        if(xhr.readyState === 4){
          if(xhr.status === 200){
            const response = JSON.parse(xhr.responseText);
            self.uploadFile(file, response.signedRequest, response.url);
          }
          else{
            alert('Could not get signed URL.');
          }
        }
      };
      xhr.send();
    }

    /*
     Function called when file input updated. If there is a file selected, then
     start upload procedure by asking for a signed request from the app.
    */
    self.initUpload = () => {
      const files = this.root.querySelector('#file-input').files;
      const file = files[0];
      if(file == null){
        return alert('No file selected.');
      }
      self.getSignedRequest(file);
    }

    self.on('mount', ()=>{
      let self = this
      // self._.navTo(null,`${subview}&target=#um&fragment=${subview}`,"#um",{},"um");
    })
  </script>
	
</aws-uploader>


<!-- 

    Step # 2
    /// server side code (node.JS can be any lang)
    
    app.get('/sign-s3', (req, res) => {
      const s3 = new aws.S3();
        s3.config.update({
            accessKeyId: process.env.S3_KEY_ID,
            secretAccessKey: process.env.S3_ACCESS_KEY_ID
        });
      const fileName = req.query['file-name'];
      const fileType = req.query['file-type'];
      const s3Params = {
        Bucket: process.env.S3_BUCKET,
        Key: fileName,
        Expires: 60,
        ContentType: fileType,
        ACL: 'public-read'
      };

      s3.getSignedUrl('putObject', s3Params, (err, data) => {
        if(err){
          console.log(err);
          return res.end();
        }
        const returnData = {
          signedRequest: data,
          url: `https://${process.env.S3_BUCKET}.s3.amazonaws.com/${fileName}`
        };
        res.write(JSON.stringify(returnData));
        res.end();
      });
    });

     Step # 3
    - setup a bucket on AWS and setup CORS settings for that. share credentaials of bucket in steap # 2 code 

 -->