index.js
function _uploadFile(incomingFd, incomingFileStream, handleProgress, s3ClientOpts, done) {
  // https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/S3.html#upload-property
  var s3ManagedUpload = _buildS3Client(s3ClientOpts)
  .upload(_stripKeysWithUndefinedValues({
    Bucket: s3ClientOpts.bucket,
    Key: incomingFd.replace(/^\/+/, ''),//« remove any leading slashes
    Body: incomingFileStream,
    ContentType: mime.getType(incomingFd)//« advisory; makes things nicer in the S3 dashboard
  }), (err, rawS3ResponseData)=>{
    if (err) {
      return done(err);
    } else {
      return done(undefined, {
        rawS3ResponseData
      });
    }
  });//_∏_

  s3ManagedUpload.on('httpUploadProgress', (event)=>{
    // console.log('upload progress');
    let written = _.isNumber(event.loaded) ? event.loaded : 0;
    let total = _.isNumber(event.total) ? event.total : undefined;
    let handledSuccessfully = handleProgress(_stripKeysWithUndefinedValues({
      name: incomingFileStream.filename || incomingFd,
      fd: incomingFd,
      written,
      total,
      percent: total ? (written / total) : undefined
    }));
    if (!handledSuccessfully) {
      s3ManagedUpload.abort();
    }
  });//œ

}
function _uploadFile(incomingFd, incomingFileStream, handleProgress, s3ClientOpts, done) {
  // https://docs.aws.amazon.com/AWSJavaScriptSDK/latest/AWS/S3.html#upload-property
  var s3ManagedUpload = _buildS3Client(s3ClientOpts)
  .upload(_stripKeysWithUndefinedValues({
    Bucket: s3ClientOpts.bucket,
    Key: incomingFd.replace(/^\/+/, ''),//« remove any leading slashes
    Body: incomingFileStream,
    ContentType: mime.getType(incomingFd)//« advisory; makes things nicer in the S3 dashboard
  }), (err, rawS3ResponseData)=>{
    if (err) {
      return done(err);
    } else {
      return done(undefined, {
        rawS3ResponseData
      });
    }
  });//_∏_

  s3ManagedUpload.on('httpUploadProgress', (event)=>{
    // console.log('upload progress');
    let written = _.isNumber(event.loaded) ? event.loaded : 0;
    let total = _.isNumber(event.total) ? event.total : undefined;
    let handledSuccessfully = handleProgress(_stripKeysWithUndefinedValues({
      name: incomingFileStream.filename || incomingFd,
      fd: incomingFd,
      written,
      total,
      percent: total ? (written / total) : undefined
    }));
    if (!handledSuccessfully) {
      s3ManagedUpload.abort();
    }
  });//œ

}
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