Change expression parsers

[JustinGeorgi]

As the community gets more involved in advanced custom widget creation, more and more users are running up against the limitations of the expression-eval library. In particular, I've seen many issues with users wanting regex expressions or js methods that require functions as parameters. Expression-eval does not handle either of these two cases.

There's a recent fork of expression-eval, jse-eval, which adopts the jsep plug-in system which, in turn would allow the addition of regex and arrow plug-ins. Is it feasible/acceptable to move MainUI from expression-eval to jse-eval?

[ghys]

Yes I knew about jse-eval and thought the same thing, but didn't look into whether or not it could be a drop-in replacement for expression-eval (or only minor changes). The goal would be to allow the extra features without breaking any existing expressions, of course.

I think it could work - it's certainly worth looking at.

[JustinGeorgi]

I was thinking of putting together a PR with a few other little tweaks to the widgets anyway. Since you're OK with it, I'll take a careful look at jse-eval and see if it's compatible while I'm doing that.

[ghys]

I think it might be fair to ping @6utt3rfly so that they know their work is being considered for inclusion as a replacement of expression-eval, as they might have additional insight.

There's an established ecosystem around these expressions, so it would be unwise to make any breaking change without careful consideration.

[6utt3rfly]

Thanks for the ping @ghys 🙂 . I had originally created the jse-eval fork, and PR to update expression-eval, but after waiting awhile, ended up publishing it as a separate package. I'm happy to help or update things if there are any conflicts between the two packages, but I believe jse-eval should be an easy drop-in replacement. It uses a newer (major) version of jsep though, which may cause some breaking changes for certain use cases (see v1.0.0 release notes). Even though jse-eval doesn't mention an eval export like expression-eval's docs, jse-eval kept it for compatibility and added evaluate to avoid warnings from lint and other tools about using eval.