Plugins for jspsych@6.1

plugins/jspsych-audio-safari-init.js

@@ -0,0 +1,87 @@
+/**
+ * jspsych-audio-safari-init
+ * Etienne Gaudrain - 2021-02-01
+ *
+ * Safari is the new Internet Explorer and does everything differently from others
+ * for better, and mostly for worse. Here is a plugin to display a screen for the user to click on
+ * before starting the experiment to unlock the audio context, if we are dealing with Safari.
+ *
+ * See https://github.com/jspsych/jsPsych/issues/1445.
+ *
+ * NOTE: When not using the WebAudio API (jsPsych initialised with `use_webaudio=false`),
+ * jspsych.js needs to be modifed to expose the list of preloaded sounds (or, it seems,
+ * at least the first one). In the code below, this is done within
+ * `jsPsych.pluginAPI.preloaded_audio_IDs()`.
+ *
+ **/
+
+jsPsych.plugins["audio-safari-init"] = (function() {
+
+    var plugin = {};
+
+    //jsPsych.pluginAPI.registerPreload('audio-safari-init', 'stimulus', 'audio');
+
+    plugin.info = {
+        name: 'audio-safari-init',
+        description: '',
+        parameters: {
+            prompt: {
+                type: jsPsych.plugins.parameterType.STRING,
+                pretty_name: 'Prompt',
+                default: "Click on the screen to start the experiment",
+                description: 'The prompt asking the user to click on the screen.'
+            }
+        }
+    }
+
+    plugin.trial = function(display_element, trial) {
+
+        // Ideally, we would want to be able to detect this on feature basis rather than using userAgents,
+        // but Safari just doesn't count clicks not directly aimed at starting sounds, while other browsers do.
+        const is_Safari = /Version\/.*Safari\//.test(navigator.userAgent) && !window.MSStream;
+        if(is_Safari){
+            display_element.innerHTML = trial.prompt;
+            document.addEventListener('touchstart', init_audio);
+            document.addEventListener('click', init_audio);
+        } else {
+            jsPsych.finishTrial();
+        }
+
+        function init_audio(){
+            var context = jsPsych.pluginAPI.audioContext();
+            if(context==null){
+                // This requires the hacked version of jspsych 6.1.0_eg2021-02-21
+                jsPsych.pluginAPI.preloaded_audio_IDs().slice(0,1).forEach(function(a){
+                    var b = jsPsych.pluginAPI.getAudioBuffer(a);
+                    b.play();
+                    b.pause();
+                    b.currentTime = 0;
+                });
+            }
+            end_trial();
+        }
+
+        // function to end trial when it is time
+        function end_trial() {
+
+            document.removeEventListener('touchstart', init_audio);
+            document.removeEventListener('click', init_audio);
+
+            // kill any remaining setTimeout handlers
+            jsPsych.pluginAPI.clearAllTimeouts();
+
+            // kill keyboard listeners
+            jsPsych.pluginAPI.cancelAllKeyboardResponses();
+
+            // clear the display
+            display_element.innerHTML = '';
+
+            // move on to the next trial
+            jsPsych.finishTrial();
+        }
+
+
+    };
+
+    return plugin;
+})();