[英]Object with generic keys in typescript
I'd like to create a common function which will take an object, then do some transformations and return new object with same keys and different values.我想创建一个通用函数,它将接受一个对象,然后进行一些转换并返回具有相同键和不同值的新对象。 I'm trying to make it "strongly-typed", so everyone who uses it will have benefits of TS and non-existing keys should throw an error.
我试图使它成为“强类型”,因此使用它的每个人都将受益于 TS 并且不存在的键应该抛出错误。
What I have for now:我现在所拥有的:
const hash = {
"first": 1,
"second": 2,
"third": 3,
}
type Mapper<T> = {
[key in keyof T]: number
}
type Result<T>= {
[key in keyof T]: () => number
}
const transform = <T>(mapper: Mapper<T>) => {
const result = {} as Result<T>
(Object.keys(mapper) as (keyof T)[]).map(key => {
result[key] = () => mapper[key]
})
return result
}
type Hash = typeof hash
const a = transform<Hash>(hash)
a.first()
// a.fifth() OK error
It works well, but I'm looking for solutions to solve this:它运作良好,但我正在寻找解决方案来解决这个问题:
Remove type assertion const result = {} as Result<T>
删除类型断言
const result = {} as Result<T>
Remove type assertion (Object.keys(mapper) as (keyof T)[])
(or use Object.entries
, but seems it also requires type assertion in this case)删除类型断言
(Object.keys(mapper) as (keyof T)[])
(或使用Object.entries
,但在这种情况下似乎也需要类型断言)
Could I implement the same, but in more "clean" way in Typescript?我可以在 Typescript 中以更“干净”的方式实现相同的功能吗?
Object.keys
returns always string[]
therefore you will need the casting. Object.keys
始终返回string[]
因此您需要进行转换。
A smaller & more robust version would use reduce
.更小、更健壮的版本将使用
reduce
。 Another small improvement would be to use the type of the original key, with T[Key]
.另一个小的改进是使用原始密钥的类型,以及
T[Key]
。
const hash = {
"first": 'someString',
"second": 2,
"third": 3,
}
type Result<T>= {
[Key in keyof T]: () => T[Key]
}
const transform = <T extends object>(obj: T): Result<T> => {
return (Object.keys(obj) as Array<keyof T>).reduce((result, key) => {
result[key] = () => obj[key];
return result;
}, {} as Result<T>)
}
const a = transform(hash)
a.first() // returns "string"
a.second() // return "number"
声明:本站的技术帖子网页,遵循CC BY-SA 4.0协议,如果您需要转载,请注明本站网址或者原文地址。任何问题请咨询:yoyou2525@163.com.