The author stated in some other comment that due to a bug multiple paths between 2 points may exist. Neither this bug got fixed, nor did the description get updated to mention this bug.

Yes, it's very irritating. Destructuring doesn't work.

Not everybody addresses their properties as object.property or object["property"]. I like to do it as .map( ({property}) => property ), and that breaks horribly.

ETA: it's not in my finished solution, but I had that in for debugging. ( turns out I was generating the list in reverse order :S )

this.in -> is that really a problem?

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I'd couple of ideas in mind to generate random tests, but I discarded those as I just realized that random tests has been added.

(But still there are no checks for cycles, though)

(other than that, that this.in is problematic as it interferes with JS default in)

I don't know if you're currently working on it, but I have an almost complete update in the forks. There are still things to sort out, tho.

No tests for invalidating cyclic graphs.

No sample tests.

Needs much more random tests.

Tests are vulnerable to input modification.

Fixed.

Name of main function in coding place is topSort but in tests its topoSort

This has now been specified.