在 object 中指定数组类型（打字稿）

Question

I know how to declare the type in a variable.

let members: string[] = []    // this works perfectly

I want to have an array of strings in an object. How can I format it correctly?

const team = {
   name: String,
   members<string[]>: [],   // this gives error!!
}

The solution

const team = {
   name: String,
   members: [] as string[]
}

Answer 1

One way is to specify the type of the whole object, just like you're doing with members - put the type of the object after a colon, before the = assignment:

const team: {
  name: StringConstructor;
  members: string[];
} = {
  name: String,
  members: [],
};

Another way is to assert the type of only the property in question with as (but I don't like this approach because I prefer to only use as to indicate to TypeScript something that there's no way of annotating otherwise).

const team = {
  name: String,
  members: [] as string[],
};