var watson = require('watson-developer-cloud');

var assistant = new watson.AssistantV1({
  username: '{username}',
  password: '{password}',
  version: '2018-07-10'
});

assistant.message({
  workspace_id: '9978a49e-ea89-4493-b33d-82298d3db20d',
  input: {'text': 'Hello'}
},  function(err, response) {
  if (err)
    console.log('error:', err);
  else
    console.log(JSON.stringify(response, null, 2));
});