如何在打字稿中使用不同类型的通用键键入对象

如何解决如何在打字稿中使用不同类型的通用键键入对象

您如何在打字稿中键入此对象？

我有一个特殊的“ datetime”键，它是一个Date，其余的键是数字。但是我不预先知道将在每个对象上设置哪些键。值示例：

type Metrics = ??????

const example1: Metrics = {
  datetime: new Date(),activity: 12.34,min: 12.34,max: 12.34,}
const example2: Metrics = {
  datetime: new Date(),avg: 12.34,}

这是我尝试过的：

type Metrics = {
  datetime: Date,[key: string]: number,}
// ERROR on the type deFinition:
// Property 'datetime' of type 'Date' is not assignable to string index type 'number'


type Metrics = { 
    datetime: Date 
} & {  
    [key: string]: number 
}
// ERROR on the variable assignment:
// Type '{ datetime: Date; activity: number; min: number; max: number; }' is not assignable to type 'Metrics'.
//   Type '{ datetime: Date; activity: number; min: number; max: number; }' is not assignable to type '{ [key: string]: number | null; }'.
//     Property 'datetime' is incompatible with index signature.
//       Type 'Date' is not assignable to type 'number'.

解决方法

您想要这样的东西：

type Metrics<K extends keyof any> = { datetime: Date } & Record<Exclude<K,"datetime">,number>;

function makeMetrics<T extends Metrics<keyof T>>(metrics: T): T {
    return metrics;
}

const example1 = makeMetrics({
    datetime: new Date(),activity: 12.34,min: 12.34,max: 12.34,});
const example2 = makeMetrics({
    datetime: new Date(),avg: 12.34,});