[英]typescript: get an key map from object with generic
我想從任何 object 中獲取密鑰 map,
我已經實現了 function,
但我不能讓 typescript 高興,
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);
您需要告訴 object 的類型,以reduce
用於蓄電池的用途。
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);
但是,我敢打賭這不是最好的解決方案。 我敢打賭,有一種方法可以像這樣編寫 function 聲明:
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"}
.
我認為這要好得多:
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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