What does the question mark mean in the return statement in JS?

Question

I've got a function service the using data from loader and transform it in the right way for me and then return new data I have a suggestion to use '?' before returning data in transformation that can make some sense if there will not be data from loader:

export default async function serviceInputSearch(url) {
  const data = await new DataLoader(url).get();
  return data?.data.results;
}

I cannot find any information in google about this '?' in return statement? What does it mean?

Answer 1

This is called optional chaining. You can find more information about it here: https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Operators/Optional_chaining.

But, given your example, the gist of it is that the question mark validates if there is a valid "data" object. If you do not have the question mark there and there is no data object or it is null, then an error will be thrown in the lines of "Cannot read the property data of 'undefined'".