Apps Script method to invoke the Cloud Natural Language API

index.js

function retrieveSentimentCF (line) {
  var apiEndpoint = 'YOUR_CLOUDFUNCTIONS_HTTPS_ENDPOINT';

  var reviewData = {
    review_text: line
  };
  
  var cfCallOptions = {
    method : 'post',
    contentType: 'application/json',
    payload : JSON.stringify(reviewData)
  };
  
  //  Invoke the Cloud Function
  var response = UrlFetchApp.fetch(apiEndpoint, cfCallOptions);
  
  var data = JSON.parse(response);
  
  var sentiment = 0.0;
  
  if (data && data.score && data.magnitude) {
     sentiment = data.score;
  }
  
  return sentiment;
}