Understanding "response = response.rt == null ? info : response;"

[SHogenboom]

I'm building my own plugin where, among other things, I want to record each key press (rt, key) while someone is typing. Looking through all the plugins I imagined that jspsych-serial-reaction-time.js would be good place to start and saw that a key press results in the after_response function being triggered:

// function to handle responses by the subject
    function after_response(info) {

     // only record first response
      response = response.rt == null ? info : response;

      if (trial.response_ends_trial) {
        endTrial();
      }
    };
};

I'm left baffled by the response = response.rt == null ? info : response; - but my gut feeling says that this is what I need to use. Can someone explain to me how the code works so I know how to use/adjust it in my experiment?

Thanks!

[SHogenboom]

The awesome tutorial video (which I hadn't watched entirely yet) obviously shows that the code above is not necessary for what I want to achieve:
https://www.youtube.com/watch?v=XQcsFwAmbiw

An answer to understand what is happening would still be appreciated though :)

[jodeleeuw]

Hi @SHogenboom. I moved this over to Discussion from Issues.

response = response.rt == null ? info : response;

This is a shorthand for an if... else statement. It's called the ternary operator. You can learn more about it here.

[SHogenboom]

Thanks! That clarifies a lot :)