jspsych-call-function

This plugin executes a specified function. This allows the experimenter to run arbitrary code at any point during the experiment.

The function cannot take any arguments. If arguments are needed, then an anonymous function should be used to wrap the function call (see examples below).

Parameters

Parameters with a default value of undefined must be specified. Other parameters can be left unspecified if the default value is acceptable.

Parameter	Type	Default Value	Description
func	function	undefined	The function to call.
async	boolean	`false`	Set to true if `func` is an asynchoronous function. If this is true, then the first argument passed to `func` will be a callback that you should call when the async operation is complete. You can pass data to the callback. See example below.

Data Generated

In addition to the default data collected by all plugins, this plugin collects the following data for each trial.

Name	Type	Value
value	any	The return value of the called function.

Examples

Calling a simple function


var myfunc = function() {
	return 'you called?';
}

var trial = {
	type: 'call-function',
	func: myfunc
}

Using an anonymous function to pass variables


var myfunc = function(data){
	// data contains all the experiment data so far,
	// so this function could implement code to write
	// the data to a database.
}

var trial = {
	type: 'call-function',
	func: function(){ myfunc(jsPsych.data.get())}
}

Async function call

var trial = {
	type: 'call-function',
	async: true,
	func: function(done){
		// can perform async operations here like
		// creating an XMLHttpRequest to communicate
		// with a server
		var xhttp = new XMLHttpRequest();
		xhttp.onreadystatechange = function() {
			if (this.readyState == 4 && this.status == 200) {
				var response_data = xhttp.responseText;
				// line below is what causes jsPsych to 
				// continue to next trial. response_data
				// will be stored in jsPsych data object.
				done(response_data);
			}
		};
		xhttp.open("GET", "path_to_server_script.php", true);
		xhttp.send();
	}
}

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