examples/conditional-and-loop-functions.html

<!DOCTYPE html>
<html>
  <head>
    <script src="../jspsych.js"></script>
    <script src="../plugins/jspsych-html-keyboard-response.js"></script>
    <link rel="stylesheet" href="../css/jspsych.css"></link>
  </head>
  <body></body>
  <script>

  var trial = {
    type: 'html-keyboard-response',
    stimulus: 'Hello. This is in a loop. Press R to repeat this trial, or C to continue.',
    choices: ['r','c']
  }

  var loop_node = {
    timeline: [trial],
    loop_function: function(data){
      if(jsPsych.pluginAPI.convertKeyCharacterToKeyCode('r') == data.values()[0].key_press){
        return true;
      } else {
        return false;
      }
    }
  }

  var pre_if_trial = {
    type: 'html-keyboard-response',
    stimulus: 'The next trial is in a conditional statement. Press S to skip it, or V to view it.',
    choices: ['s','v']
  }

  var if_trial = {
    type: 'html-keyboard-response',
    stimulus: 'You chose to view the trial. Press any key to continue.'
  }

  var if_node = {
    timeline: [if_trial],
    conditional_function: function(){
      var data = jsPsych.data.get().last(1).values()[0];
      if(data.key_press == jsPsych.pluginAPI.convertKeyCharacterToKeyCode('s')){
        return false;
      } else {
        return true;
      }
    }
  }

  var after_if_trial = {
    type: 'html-keyboard-response',
    stimulus: 'This is the trial after the conditional.'
  }

  jsPsych.init({
    timeline: [loop_node, pre_if_trial, if_node, after_if_trial],
    on_finish: function(){ jsPsych.data.displayData(); },
    default_iti: 200
  });

  </script>
</html>