如何定义接口中所有属性的类型？

Question

I'm defining an interface which provides strings in i18n application:

interface ILocaleStringsProvider {
  'foo': string
  'bar': string
  'baz': string
  'blablabla': string
  // hundreds of string properties here...
}

I don't like to repeat : string many times.

Is there a way to define the type of all properties at a time?

Answer 1

You could use the Record<K extends string, T> type. If you have different types for different fields you can use union types:

type ILocaleStringsProvider = 
    Record<'foo'|'bar'|'baz'|'blablabla',string> &
    Record<'foo2'|'bar2'|'baz2'|'blablabla2',number>;

Answer 2

You could use Index, Union and in:

type ILocaleStringsProvider = {
    [i in 'foo' | 'bar' | 'baz' | 'blablabla']: string
}