plugin.trial = function()

in datawig-js/static/jspsych-6.1.0/plugins/jspsych-video-keyboard-response.js [103:233]

• 68 lines of code
• 15 McCabe index (conditional complexity)

  plugin.trial = function(display_element, trial) {

    // setup stimulus
    var video_html = '<div>'
    video_html += '<video id="jspsych-video-keyboard-response-stimulus"';

    if(trial.width) {
      video_html += ' width="'+trial.width+'"';
    }
    if(trial.height) {
      video_html += ' height="'+trial.height+'"';
    }
    if(trial.autoplay){
      video_html += " autoplay ";
    }
    if(trial.controls){
      video_html +=" controls ";
    }
    video_html +=">";

    var video_preload_blob = jsPsych.pluginAPI.getVideoBuffer(trial.sources[0]);
    if(!video_preload_blob) {
      for(var i=0; i<trial.sources.length; i++){
        var file_name = trial.sources[i];
        if(file_name.indexOf('?') > -1){
          file_name = file_name.substring(0, file_name.indexOf('?'));
        }
        var type = file_name.substr(file_name.lastIndexOf('.') + 1);
        type = type.toLowerCase();
        video_html+='<source src="' + file_name + '" type="video/'+type+'">';   
      }
    }
    video_html += "</video>";
    video_html += "</div>";

    // add prompt if there is one
    if (trial.prompt !== null) {
      video_html += trial.prompt;
    }

    display_element.innerHTML = video_html;

    if(video_preload_blob){
      display_element.querySelector('#jspsych-video-keyboard-response-stimulus').src = video_preload_blob;
    }

    display_element.querySelector('#jspsych-video-keyboard-response-stimulus').onended = function(){
      if(trial.trial_ends_after_video){
        end_trial();
      }
    }

    if(trial.start !== null){
      display_element.querySelector('#jspsych-video-keyboard-response-stimulus').currentTime = trial.start;
    }

    if(trial.stop !== null){
      display_element.querySelector('#jspsych-video-keyboard-response-stimulus').addEventListener('timeupdate', function(e){
        var currenttime = display_element.querySelector('#jspsych-video-keyboard-response-stimulus').currentTime;
        if(currenttime >= trial.stop){
          display_element.querySelector('#jspsych-video-keyboard-response-stimulus').pause();
        }
      })
    }

    display_element.querySelector('#jspsych-video-keyboard-response-stimulus').playbackRate = trial.rate;

    // store response
    var response = {
      rt: null,
      key: null
    };

    // function to end trial when it is time
    function end_trial() {

      // kill any remaining setTimeout handlers
      jsPsych.pluginAPI.clearAllTimeouts();

      // kill keyboard listeners
      jsPsych.pluginAPI.cancelAllKeyboardResponses();

      // gather the data to store for the trial
      var trial_data = {
        "rt": response.rt,
        "stimulus": trial.stimulus,
        "key_press": response.key
      };

      // clear the display
      display_element.innerHTML = '';

      // move on to the next trial
      jsPsych.finishTrial(trial_data);
    };

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

      // after a valid response, the stimulus will have the CSS class 'responded'
      // which can be used to provide visual feedback that a response was recorded
      display_element.querySelector('#jspsych-video-keyboard-response-stimulus').className += ' responded';

      // only record the first response
      if (response.key == null) {
        response = info;
      }

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

    // start the response listener
    if (trial.choices != jsPsych.NO_KEYS) {
      var keyboardListener = jsPsych.pluginAPI.getKeyboardResponse({
        callback_function: after_response,
        valid_responses: trial.choices,
        rt_method: 'performance',
        persist: false,
        allow_held_key: false,
      });
    }

    // end trial if time limit is set
    if (trial.trial_duration !== null) {
      jsPsych.pluginAPI.setTimeout(function() {
        end_trial();
      }, trial.trial_duration);
    }
  };