当我检查值是否在前一行中定义时，为什么 Typescript 会抱怨可能的未定义值？

Question

I have this code, I'm wondering why Typescript is complaining, the function isNextWeek expects a string and here the code complains that argument of type string or undefined is not assignable, but aren't I checking for the localTime being defined in the localTimeExists check - so it should never call the function if it's undefined.

Not sure why it's complaining, or if anyone has suggestions to avoid this issue. I did manage to avoid it by wrapping it in an 'if' condition but then that scopes the value to that block and I want to use it outside so wondered if there is another way. Thanks

const localTimeExists = !!out && !!out.localTime;
const doThis = !isToday && localTimeExists && isNextWeek(out.localTime);

Answer 1

引用对我有用的@Bergis 评论 - 我通过将真实检查内联来实现这一点，因为在进行推理时将其提取到一个单独的行中混淆了 Typescript。