Question

尝试运行以下内容：

type Mode = 'signup' | 'signin' | 'forgot-password';

interface IProps {}

interface IState {
  mode: Mode;
}

class SigninSignupModal extends React.Component<IProps, IState> {
  state = {
    mode: 'signup',
  };
}

引发以下错误：

Type 'string' is not assignable to type 'Mode'. ts(2416)

那是为什么？

例如，这很好：

type Mode = 'signup' | 'signin' | 'forgot-password';

let mode: Mode = 'signup';

而且，这很好：

class SigninSignupModal extends React.Component<IProps, IState> {
  construct() {
    this.state = {
      mode: 'signup',
    };
  }
}

Answer 1

我想您必须将string强制转换为Mode类型：

this.state = {
  mode: 'signup' as Mode,
};

或

    this.state = {
      mode: <Mode>'signup',
    };

有关更多信息，请滚动至“类型断言”： https://www.typescriptlang.org/docs/handbook/basic-types.html

设置状态的接口包含枚举值会引发错误

1 个答案: