Get array of synonyms from natural nodes s wordnet - NodeJS

Question

I'm attempting to develop a function that takes a word and returns an array containing all synonyms discovered using NaturalNode's wordnet lookup function (https://github.com/NaturalNode/natural ).

I'm having trouble returning the final array, though. My issue, I believe, has to do with scopes. I have the right array if I log the array during the wordnet lookup. This, however, appears to have no effect on the array I'm trying to return.

var getSynomyns = function(keyword){
    var synonymsArr = [];
    console.log(`GETTING SYNOMYNS FOR ${keyword}`);

    wordnet.lookup(keyword, function(results){
        results.forEach(function(result){
            result.synonyms.forEach(function(syn){
                if(synonymsArr.indexOf(syn) === -1){
                    synonymsArr.push(syn);
                }
            });
        });
    console.log(synonymsArr);
    //return synonyms;
    });
    return synonymsArr;
}

For instance, if I enter the word 'test' into the function, I want it to return all synonyms for 'test.' It, on the other hand, just returns an empty array.

Please let me know if anything is unclear, and thank you for your assistance:)

EDIT: I understand this is a popular question, but the tagged duplicate doesn't provide a clear response for me. It would be very appreciated if someone could explain using my code.

Answer 1

You can't return values in an async world. Everything that has to be done when the value is ready should be done within the callback. Another option is to use promises. The es6-promise package is required:

var Promise = require('es6-promise').Promise;

var asyncJobInfo = function(jobID) {
  var oozie = oozieNode.createClient({config: config});
  var command = 'job/' + jobID + '?show=info';
  console.log("running oozie command: " + command);
  // Creates a new promise that wraps
  // your async code, and exposes two callbacks:
  // success, and fail.
  return new Promise(function(success, fail) {
    oozie.get(command, function(error, response) {
      if (error) {
        fail(error);
      } else {
        success(response);
      }
    });
  });
};

Now you can use the promise and pass the callbacks that will run once it is resolved:

exports.getJobInfoByID = function(req, res) {
  asyncJobInfo(req.params.id).then(function(data) {
    res.send(data)
  }).catch(function(error) {
    console.error(error);
  });
};

The above can be shortened:

exports.getJobInfoByID = function(req, res) {
  asyncJobInfo(req.params.id)
    .then(res.send.bind(res))
    .catch(console.error);
};