title: Node.js: can you use asynchronous functions from within streams?
body: <p>Consider the following:</p>
  
  <pre><code>var asyncFunction = function(data, callback) {
    doAsyncyThing(function(data){
      // do some stuff
      return callback(err)
    })
  }
  fs.createReadStream('eupmc_lite_metadata_2016_04_15.json')
    .pipe(JSONstream.parse())
    .on('data', asyncFunction)   // &lt;- how to let asyncFunction complete before continuing
  </code></pre>
  
  <p>How does the stream know when asyncFunction has completed? Is there any way to use asynchronous functions from within streams?</p>