Type Predicate Inference: The TS 5.5 Feature No One Expected

Matt PocockMatt is a well-regarded TypeScript expert known for his ability to demystify complex TypeScript concepts. TypeScript 5.5 will be dropping in the next couple of months. And thanks to one PR in particular, I already know it's going to be an incredible release. On Friday night, TypeScript merged Dan Vanderkam's PR to "Infer type predicates from function bodies using control flow analysis".

[jay-es]

TS 5.5 では関数本体から型述語が推論されるようになる（is を書かなくてもよい）。式を組み合わせて複雑なオブジェクトの絞り込みも可能。ただし `.filter(Boolean)` はおそらく従来通り