如何确保函数支持两种接口类型？

Question

我有一个名为printForm的函数，它需要同时支持两个接口IOldForm(旧版env)和INewForm(新env)，但它存在以下问题：

interface IOldForm {
  formDescription: string;
  formId: string;
  isOpt: boolean;
  incude?: boolean;
}

interface INewForm extends Pick<IOldForm, "formDescription"> {
  type: string;
  route: string;
}

const oldForm = {
  formDescription: "oldForm",
  formId: "123",
  isOpt: true
};

const newForm = {
  formDescription: "newForm",
  type: "newForm",
  route: "456"
};

const test = (trans: INewForm) => {
  console.log(trans);
};

const printForm = (form: IOldForm | INewForm): void => {
  console.log(form.isOpt);
  test(form);
};

printForm(oldForm);

printForm(newForm);

​

​

如何解决这个问题以确保printForm同时支持oldForm和newForm类型？谢谢。

Answer 1

您必须首先检查您的类型是否为IOldForm或INewForm。就像这样：

​

const printForm = (form: IOldForm | INewForm): void => {
// by checking this typescript will be informed that which type you wanna use
if("isOtp" in form){
  console.log(form.isOpt);
  test(form);
  }
};

​

Answer 2

const printForm = (form: IOldForm | INewForm): void => {
  const { isOpt } = form as IOldForm;
  console.log(isOpt);
};

printForm(oldForm);

我们可以使用类型断言来解决这个问题。