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JavaScript

Posted by dylancascio
dylancascio
11,400 Points

Promise is returned with incomplete data

Hi, I just came across this problem when working on the "How many people are in space" video and thought it might help to share the workaround I came up with.

The Promise from getProfiles is being correctly returned, however one of the astronauts has a common name at this current time. Wikipedia returns a "disambiguation" page instead of a "standard" page. This means that in generateHTML when the template literal is being constructed for the <img> element, person.thumbnail is undefined.

Edit: to clarify, this means that the JSON is properly returned, but execution is halted during HTML generation and the elements are not displayed.

dylancascio
dylancascio
11,400 Points

As a workaround, I created a new function to check for a disambiguous entry to handle this particular case and add in a thumbnail.source property to allow execution to continue. Finally, I used .then() after getting the JSON for each person and passed the person object to the new disambiguous checker:

function isDisambiguous(entry) {
  const disambImg = "https://i.kym-cdn.com/photos/images/original/001/285/460/8b6.jpg"
  if (entry.type === "disambiguation") {     // handle the disambiguation case
    entry.thumbnail = {
      source: disambImg                      // add missing image url
    };
  } return entry                             // return person object, changed or unchanged
}

function getProfiles(json) {
  const profiles = json.people.map(person => {
    return getJSON(wikiUrl + person.name)    // get our regular data
      .then(isDisambiguous);                 // check for disambiguation
  });
  return Promise.all(profiles);
};```

1 Answer

Zimri Leijen
Zimri Leijen
11,835 Points
Zimri Leijen
Zimri Leijen
11,835 Points

Yeah, I had that same problem. You can either ignore it, or make a workaround to catch that issue.

There are a couple of astronauts with ambiguous names.