Is there a way Typescript can correctly infer that array.at(x) must be defined?

Sasgorilla 0
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Let's say I have an array that might be empty:

const cheeses: string[] = ...

console.log('my favorite cheese is ', 
  cheeses.length > 0 ? cheeses.at(-1)?.toUpperCase() : 'GORGONZOLA'
)

This throws a type error at cheeses.at(-1): Object is possibly undefined.

I can fix it with (much uglier) cheeses[cheeses.length - 1].toUpperCase() (though that in fact seems to circumvent any type guard, since I can also call [cheeses.length - 10] without error.)

Is there a way to make Typescript (4.6.x) infer that cheeses.at(-1)? must be defined?

typescript
0 Answers
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