Non-existing properties are truthy

[dannybloe]

Howdee,

Just upgraded to 3.1.0 and noticed this weird change. De expression "nonexistingsomething" is now truthy if there is no value for 'nonexistingsomething'. Previously this was falsy. That is quite serious. Normally undefined is false.
Am I missing something here?

[cshaa]

Hey!
Sorry for taking such a long time to respond, I've been through a turbulent time in my life. The change that caused this was me adding a try-catch so that it's guaranteed that filtrex functions never throw. However, the way I implemented this was quite unfortunate, as I just return the error, and errors are truthy. I will release a new version that uses the more idiomatic Result-style outputs, in the same vein that promises and iterators already do in JavaScript: [1] [2]

type PromiseSettledResult<T> = { status: 'fulfilled', value: T } | { status: 'rejected', reason: any }
type IteratorResult<Val, Ret> = { done: false, value: Val } | { done: true, value: Ret }

// this would be the new return type of filtrex functions:
type FiltrexResult = { success: true, value: any } | { success: false, reason: any }

Would something like that solve the issue for you? Or would it be too cumbersome to use?

[dannybloe]

Hi, thanks for working on this.
I don't exactly what the impact is of this change. For me it would be fine if I don't have to change anything and that it just returns false. But your solutation may work as well 🙂

[zirkelc]

@cshaa I just stumbled upon this issue. I think the Result type would be find. Another option might be to do it Zod-style and have a throwing and non-throwing version of the filter expression:

const expression = compileExpression('a and b'); // throws

const expression = compileSafeExpression('a and b'); // non-throwing, returns success