Conceptual idea

etl-runner.js

import async from 'async';

export default class ETLRunner {
  constructor(extractor, transformer, loader) {
    this.extractor = extractor;
    this.transformer = transformer;
    this.loader = loader;
  }

  extract(callback) {
    const data = this.extractor();
    callback(null, data);
  }
  transform(data, callback) {
    const transformedData = this.transformer(data);
    callback(null, transformedData);
  }

  load(data, callback) {
    this.loader(data);
    callback(null, 'done');
  }

  run() {
    async.waterfall([
      this.extract,
      this.transform,
      this.load,
    ], (err, result) => {
      console.log(result); // result equals 'done'
    });
  }
}