[英]typescript: get an key map from object with generic
I want to get the key map from any object,我想从任何 object 中获取密钥 map,
I've implemented the function,我已经实现了 function,
but I can't make typescript happy,但我不能让 typescript 高兴,
what should I do without using acc: any
如果不使用
acc: any
const origin = {
a: 1,
b: 'string',
c: () => {}
};
function getObjKeyMap<T>(obj: T) {
return Object.keys(obj).reduce((acc, k) => {
/* Element implicitly has an 'any' type because expression of type 'string' can't be used to index type '{}'.
No index signature with a parameter of type 'string' was found on type '{}'.ts(7053) */
acc[k] = k;
return acc;
}, {});
}
const keyMap = getObjKeyMap(origin);
You need to tell the type of object that reduce
uses for accumulator.您需要告诉 object 的类型,以
reduce
用于蓄电池的用途。
const originObj = {
a: 1,
b: 'string',
c: () => {}
};
function getObjKeyMap<T>(obj: T) {
return Object.keys(obj).reduce((acc, k) => {
acc[k] = k;
return acc;
}, {} as Record<string, string>);
}
// or
function getObjKeyMap1<T>(obj: T) {
return Object.keys(obj).reduce((acc: Record<string, string>, k: string) => {
acc[k] = k;
return acc;
}, {});
}
const keyMap = getObjKeyMap(originObj);
However, I bet this is not the best solution.但是,我敢打赌这不是最好的解决方案。 I bet there is a way to write a function declaration like this:
我敢打赌,有一种方法可以像这样编写 function 声明:
function getObjKeyMap<T, K extends keyof T>(obj: T): Record<K, K>
Where Typescript automatically tells you that getObjectMap({a: 1, b: 'string', c: () => {}}
returns {a: "a", b: "b", c: "c"}
. Where Typescript automatically tells you that
getObjectMap({a: 1, b: 'string', c: () => {}}
returns {a: "a", b: "b", c: "c"}
.
I think this is much better:我认为这要好得多:
const originObj = {
a: 1,
b: 'string',
c: () => {}
};
type KeyMap<T> = {
[key in keyof T]: key
};
function getObjKeyMap<T>(obj: T): KeyMap<T> {
return Object.keys(obj).reduce((acc, k) => ({...acc, k: k}), {} as KeyMap<T>);
}
const keyMap = getObjKeyMap<typeof originObj>(originObj);
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