jspsych-waitfor-function

This plugin executes a specified function and displays a spinning wheel while waiting for the function to complete. 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).

This plugin is based on jspsych-call-function.

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. See the `async` argument for details.
async	boolean	`false`	If set to true, `func` will be executed asynchoronously. In that case, the first argument passed to `func` is a callback that jsPsych will pass to it, and that you need to call when the async operation is complete. This callback can receive data as argument, that will be added to the trial's data. See example below.
min_duration	int	0	The spinner will be displayed at least this time. Value in milliseconds.

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.

Dependencies

The spinner is currently using Semantic UI's loader, so you need to add the related CSS (and its dependencies) to your page, or the whole Semantic CSS.

Examples

Async function call

When doing an asynchronous function call, the function needs to take a argument that will be a callback function (called done in the example below), and you need to execute that callback when the function is done doing its work:

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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