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PsychoPy Python to Javascript crib sheet

Many people come to this forum because their experiment works fine locally but doesn’t work online. The reason is that the Python code needs to be translated to Javascript and the auto translate that was added to PsychoPy in January 2020 primarily translates the grammar rather than the individual functions.

If you want to run PsychoPy online I highly recommend that you:

  1. Write your experiment in Builder using version 2020.1.3 (or later).

  2. Study my crib sheet to familiarise yourself with the aspects that need manual translation or additional definitions.

  3. Where possible try to write the experiment so it works both locally and online. Some errors are easier to spot locally.

  4. Make suggestions to the crib sheet if you have a fix that can help others.

Best wishes,


Wakefield Morys-Carter MA (he/him)
Senior Psychology Demonstrator and Teaching Fellow
Oxford Brookes University
Treasurer and Membership Secretary
Association of Technical Staff in Psychology (ATSiP)

Vertical Enhancement of Statistics and Psychology Research
Twitter: @Psych_Stats #VESPRox


I think it is super useful. I wish I had seen it before coding my first online experiment! :slight_smile:
I would also add that it is possible to test the online version on your local computer e.g. by means of IIS in Windows. And if you use Visual Studio Code, then there is an extension, which makes the process even easier: IIS Express.

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@aisa2 has written a companion document for people needing help with getting started.