Behavior of loop_function in jsPsych version 8

[kurokida]

Hi, all,

The following code is a sample program using the survey-likert plugin, and it is expected to display a random number in the question items for each trial.

    var jsPsych = initJsPsych({
      on_finish: function() {
        jsPsych.data.displayData();
      }
    });

    var scale = ["Strongly Disagree", "Disagree", "Neutral", "Agree", "Strongly Agree"];

    var likert_trial = {
        type: jsPsychSurveyLikert,
        questions: [
          {
            prompt: function(){
                return Math.random()
            }, 
            name: 'Vegetables', labels: scale, required: true},
          {prompt: "I like fruit.", name: 'Fruit', labels: scale, required: true}
        ],
    };

    const loop_node = {
        timeline: [likert_trial],
        loop_function: function(data){
            return true
        }
    }

    jsPsych.run([loop_node]);

The above code works fine in jsPsych version 7.3.2, but, in version 8.2.1, the numbers do not change randomly and a fixed number is displayed. I am unsure whether this is a bug or the behavior of loop_function has changed. If it is the latter, how should I modify the code?

Best regards,
Daiichiro

[kurokida]

Hi developers,

Thank you as always for maintaining the library. This is a reminder — the issue I previously reported here still seems to persist in version 8.2.2. I would appreciate it if you could take a look.

Best ragards,
Daiichiro

[jodeleeuw]

I suspect what is broken in version 8 is the evaluation of the function parameter in the likert_trial.

What happens if you do this instead?

questions: function() {
  return [
    {
      prompt: Math.random(),
      name: 'Vegetables', 
      labels: scale, 
      required: true
    },
    {prompt: "I like fruit.", name: 'Fruit', labels: scale, required: true}
 ]

[kurokida]

Thank you for your prompt reply. Your code works perfectly.

It would be really helpful if you could make it work with my approach as well, since it used to work in version 7.

Best ragards,
Daiichiro