node.js script fails - TypeError: Object 0 has no method 'on' - Mac to Arduino UNO

Question

when I attempt to run this uvsensor.js script from this plot.ly tutorial I encounter this error message. What is the best way to resolve it?

uv-sensor-tutorial $ node uvsensor.js
1421612122362 Device(s) /dev/cu.usbmodem1411
1421612125588 Connected /dev/cu.usbmodem1411
1421612125588 Repl Initialized
>> { streamstatus: 'All Streams Go!',
  url: 'https://plot.ly/~micahstubbs/46',
  message: '',
  warning: '',
  filename: 'uv sensing nodey arduino!',
  error: '' }

/Users/m/workspace/arduino-projects/uv-sensor-tutorial/uvsensor.js:76
    refLevel.on("data", function() {
             ^
TypeError: Object 0 has no method 'on'
    at /Users/m/workspace/arduino-projects/uv-sensor-tutorial/uvsensor.js:76:14
    at /Users/m/node_modules/plotly/index.js:87:17
    at IncomingMessage.<anonymous> (/Users/m/node_modules/plotly/index.js:255:9)
    at IncomingMessage.EventEmitter.emit (events.js:117:20)
    at _stream_readable.js:920:16
    at process._tickCallback (node.js:415:13)

Answer 1

The best way to resolve it is to find out why refLevel is being assigned 0 instead of the object you think it should be.