feat: add isClass function

[MarlonPassos-git]

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Summary

Add the isClass function

 isClass(class CustomClass {}) // => true
 isClass('abc') // => false
 isClass({}) // => false

In the documentation, I emphasized that this function primarily validates whether a value is a custom class using the class syntax, rather than checking if the value is compatible with new. If we wanted to handle all cases of instantiable objects, including old-school function-based classes and “native classes”, we should implement separate functions for these cases. This function does not account for function constructors or native classes that can still be instantiated with new.

If we were to address this, we could consider implementing a separate utility, perhaps using an approach like this: https://www.npmjs.com/package/isclass?activeTab=code

Related issue, if any:

For any code change,

• Related documentation has been updated, if needed
• Related tests have been added or updated, if needed
• Related benchmarks have been added or updated, if needed

Does this PR introduce a breaking change?

No

Bundle impact

Status	File	Size 1
A	src/typed/isClass.ts	148

Footnotes

1. Function size includes the import dependencies of the function. ↩

[radashi-bot]

Benchmark Results

Name	Current
isClass: with class	606,360.55 ops/sec ±5.08%
isClass: with non-class	4,049,967.1 ops/sec ±0.06%

Performance regressions of 30% or more should be investigated, unless they were anticipated. Smaller regressions may be due to normal variability, as we don't use dedicated CI infrastructure.

[aleclarson]

Thank you for this 😎

I tweaked the Class type and the return type of isClass to be even more robust. Also added more “type test” cases.

[aleclarson]

Hey! There's a new requirement for PRs that introduce new features. Without this requirement met, we won't be able to merge this. Note that this PR can still be included in a beta prerelease before this requirement is fulfilled.

• Edit the next-minor.md file