[satisfies](https://www.typescriptlang.org/docs/handbook/release-notes/typescript-4-9.html#the-satisfies-operator) 操作符

用于确保表达式与指定的类型匹配，但不影响返回的类型。

官方示例（具体说明点上面标题的链接）：

type Colors = "red" | "green" | "blue";
type RGB = [red: number, green: number, blue: number];
const palette = {
 red: [255, 0, 0],
 green: "",
 bleu: [0, 0, 255]
// ~~~~ The typo is now caught!
} satisfies Record<Colors, string | RGB>;
// Both of these methods are still accessible!
const redComponent = palette.red.at(0);
const greenNormalized = palette.green.toUpperCase();