我可以定义一个枚举和函数的打字稿变量吗？

Question

Here is the code so far:

function fr(this: any, value: number) {
  return Object.keys(this).find(k => this[k] === value);
}

type getEnumValue = (value: number) => string;
type myEnum = typeof enumVal;

enum enumVal {
  a = 1,
  b = 2
}

let EnumEval = fr.bind(enumVal) as getEnumValue | myEnum;
Object.assign(EnumEval, enumVal);

// Why are the casts required?
console.log((EnumEval as myEnum).a);
console.log((EnumEval as getEnumValue)(1));

console.log(EnumEval as myEnum.a);
console.log(EnumEval(1));

TS errors on the final two lines, requiring me to cast. Why?

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Answer 1

Here you go:

let EnumEval = fr.bind(enumVal) as (((value:number) => string) & (typeof enumVal));

Or:

let EnumEval = fr.bind(enumVal) as (typeof fr & typeof enumVal);

Variable that is an enum and a function - so it should be intersection ( & ), not a union ( | )

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