es-writable-stream-5.js

class ElasticSearchWritableStream extends stream.Writable {
  constructor(config, options) {
    super(options)
    this.config = config
    
    /**
     * Create the ElasticSearch client:
     */

    this.client = new elasticsearch.Client({
      host: this.config.host
    })
  }
  
  ...
}