Saving data when user closes browser unexpectedly

[wuaham]

Hello,

I wish to save data whenever participants leave or closes the browser. I called on_close call back in jsPsych.init but it is now working if I leave/close the browser unexpectedly.

Do I need to add any plugin in my script for this please?

Thank you.

[becky-gilbert]

Hi @wuaham, no you shouldn't need to add any plugins for this. You should just be able to save your data in the on_close function in jsPsych.init, as in the example shown in the on_close function documentation. So I'm not sure why this isn't working. Would you mind sharing your code please?

[becky-gilbert]

Hi @wuaham, very sorry for the slow response.

You could try checking that the experiment's on_close function is being called by adding an alert inside the function:

alert("The experiment isn't finished. Are you sure you want to leave the page?");

Another thing you could try is calling the function to get the CSV data first, to make sure that that function completes before the save data function is called. It might be that the page is closed right after the saveData function is called, which means that jsPsych's csv function doesn't have the chance to complete.

var data = jsPsych.data.get().csv();
saveData(..., data);

@jodeleeuw not sure how to debug this since closing the page also closes the developer tools. Any ideas?

[jodeleeuw]

I think the issue is that the browser may stop executing the request to the server when the page closes. If you are sending 64kB of data or less, then you can use the Fetch keepalive method.

We should probably update the docs so that it is clear that you are limited in what you can execute in this part of the code.

[marahaslam]

Hi! I tried to add an alert re: Becky's suggestion above, and the alert never happens. This indicates that on_close isn't being called at all.

[jodeleeuw]

Is this using the latest version of jsPsych?

[marahaslam]

Yes, when I run an experiment using 6.2.0 and close the tab before the experiment is done, it doesn't give an alert.

jsPsych.init({
    /*display_element: $('#jspsych-target'),*/
    timeline: [start_the_experiment, consent_protected_timeline, end_the_experiment],
    exclusions: {audio: true},
    preload_audio: audio,
    preload_images: images_to_preload,
    show_progress_bar: false,
    /*auto_update_progress_bar: true,*/
    on_close: function(){ 
        alert("The experiment isn't finished. Are you sure you want to leave the page?");
        var filename = "ortho_data_" + subjectID + ".csv";
        saveData(filename, jsPsych.data.get().csv());
        /*jsPsych.setProgressBar(1);*/
        console.log("data saved.");
    }
});