javascript - typescript 不打字

Question

我正在尝试从处于 react 状态的对象调用函数

//currentUser is of type User
this.state.currentUser.rankUp()

但它只是给出了一个错误this.state.currentUser.rankUp is not a function。如果我创建一个新的用户对象，但它确实让我调用所述函数。即使我尝试将其转换为用户: var user:User = this.state.currentUser as User 然后调用它给出的函数同样的错误。我尝试打印类型，即使在转换它时，它也会返回为 object 而不是 User

到目前为止，我设法让它工作的唯一方法是 user.rankUp = (new User("a")).rankUp; 尽管它有效，但感觉它不正确.

编辑:

User.rankUp 定义为:

rankUp(){
    this.rank +=1;
}

Answer 1

Even if I try casting it as user: var user:User = this.state.currentUser as User then calling the function it gives the same error.

TypeScript 没有类型转换。它有类型断言:https://basarat.gitbooks.io/typescript/docs/types/type-assertion.html

The reason why it's not called "type casting" is that casting generally implies some sort of runtime support. However type assertions are purely a compile time construct and a way for you to provide hints to the compiler on how you want your code to be analyzed.

所以回答你的问题:

Typescript not typecasting

因为没有类型转换。 🌹