randomFromStream

randomFromStream.js

function randomFromStream(currentResult, length) {
  var potentialResult = gfs();

  // no more numbers in stream
  if (potentialResult === null) {
    return currentResult;
  }
  
  length += 1;
  
  if (Math.floor(Math.random() * length === 0)) {
    currentResult = potentialResult;
  }
  
  return randomFromStream(currentResult, length);
}

randomFromStream(null, 0);