Promisifying listeners

Question

I was a huge promise chain, however I realized that one of the functions returns an object that has listeners and react to callbacks like

object.on('data', function(err, data) {
     //do something
});

object.on('exit', function(err, data) {
     //do something
});

I was wondering if there was a way to work this using promises and turn them into thenables. Is there no alternative to rewriting my entire promise chain to use callbacks?

Suggested duplicate shows code converting callbacks and promises to each other. For node.js specific conversion check what promise library you use and adopt conversion code accordingly. — Alexei Levenkov, Dec 17 '15 at 05:51

score 5 · Answer 1 · edited Dec 17 '15 at 08:32

5

Can't you wrap the object?

var promiseForObjectData = new Promise(function(resolve, reject) {

  // Note that you can't promisify data, because it gets called multiple times.
  object.on('data', function(err, data) {
    if (err) return reject(err);
    //do something
  });

  object.on('exit', function(err, data) {
    if (err) return reject(err);
    return resolve(...whatever...);
  });

});

edited Dec 17 '15 at 08:32

Madara's Ghost

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answered Dec 17 '15 at 06:41

robertklep

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Promisifying listeners

1 Answers1