Developer Tools
Use Developer Tools (Ctl-Shift-I in Windows/Chrome, Cmd-Opt-J or Cmd-Opt-I in Mac/Chrome, F12 in IE/Edge, Ctrl-Shift-J in Windows/Safari, Ctrl-Opt-J in Mac/Safari) to view errors via the browser console if you aren’t getting sufficient information from PsychoPy. You can add print(var) (which translates to console.log(var); ) to check the value of a variable var at a particular point. N.B. If you need to stop your participants doing this and being able to view trial variables you may be loading from Excel, add log4javascript.setEnabled(false); to code_JS [sotiri]. This will prevent cheating on experiments with a performance based reward.
Tutorial: Thomas Pronk / tutorial_js_console_log · GitLab
See also Tech Support & Bug Report Guidelines
(I’m usually on my phone so it’s not easy to copy and paste)