有没有办法只限制参数中的联合类型？

Question

我试图将函数的参数限制为仅联合类型。

例如：

type UnionType = readonly string[];

const getSelector = <T extends UnionType>(arg: T)=>{
  return (validType: T[number])=>{
    return 'data is '+(!arg.includes(validType) ? "NOT " : '') + "included";
  }
}

const myFunc = getSelector(["opt1", "opt2", "opt3"] as const); // <== should be fine!
myFunc("opt1"); // auto complete is working!

const myFunc2 = getSelector(["optA", "optB", "optC"]);
myFunc2("optA"); // auto complete is NOT working! since the given options are not const.
// how can I RESTRICT the options as const type?

正如您在上面的示例中看到的，我尝试使用

readonly

关键字来创建扩展类型。我也尝试过

Readonly<string[]>

。多次试验可能没有意义，所以不在这里分享，但我想知道是否有一种方法可以使其成为可能。

Answer 1

只需升级泛型类型即可：

const getSelector = <T extends string>(arg: T[])=>{
  return (validType: T) =>{
    return 'data is '+(!arg.includes(validType) ? "NOT " : '') + "included";
  }
}

const myFunc = getSelector(['opt1', "opt2", "opt3"] as const); // <== should be fine!
myFunc('opt1'); // auto complete is working!

const myFunc2 = getSelector(["optA", "optB", "optC"]);
myFunc2('optA'); // auto complete is NOT working! since the given options are not const.
// how can I RESTRICT the options as const type?