Request for JS Concat

Online experiments
1

Hi Team,

I’m not sure of the best place to submit feature requests. Should they be posted here, on the GitHub Issues page, or somewhere else?

We’ve recently discovered a bug in our experiment code that resulted in incorrect data being recorded. As part of our analysis workflow, we were calculating a standard deviation and needed to combine two lists. Because of the Auto->JS translation, the code ran without error, but the lists were joined using JavaScript’s + operator behaviour rather than Python list concatenation. As a result, two adjacent values were merged together, producing invalid output and ultimately affecting our results.

Wakefield has kindly put together a guide explaining this behaviour and how to avoid it. However, I wondered whether this could be addressed directly in the Auto->JS translation process.

Would it be possible for expressions such as:

Python

  • list1 + list2

to be translated to:

JavaScript

  • list1.concat(list2)

rather than:

JavaScript

  • list1 + list2

This would more closely match Python’s behaviour for list concatenation and could help prevent subtle data-processing bugs that are difficult to detect until much later in the analysis pipeline.

I appreciate there may be technical reasons why this isn’t straightforward, but I thought it would be worth raising as a potential improvement.

Thanks!

2

The main reason why this isn’t straightforward is because you are asking for a + b to translate to different things depending on what a and b actually are. This may not be obvious from the code, and could change at any moment. I would recommend having a custom function defined in a Both component so it works the same way in both environments.