Question

这两个初始化不应该等效吗？

这行得通：

private screensMap: Map<string, ComponentType<any>>;

public constructor() {
    this.screensMap = new Map()
        .set(BootstrapLaunch.name, BootstrapLaunch)
        .set(BootstrapWelcome.name, BootstrapWelcome);
}

但这失败了：

private screensMap: Map<string, ComponentType<any>>;

public constructor() {
    this.screensMap = new Map([
        [BootstrapLaunch.name, BootstrapLaunch],
        [BootstrapWelcome.name, BootstrapWelcome],
    ]);
}

出现下一个错误：

error TS2345: Argument of type '([string, typeof BootstrapLaunch] | [string, typeof BootstrapWelcome])[]' is not assignable to parameter of type 'ReadonlyArray<[string, typeof BootstrapLaunch]>'.
  Type '[string, typeof BootstrapLaunch] | [string, typeof BootstrapWelcome]' is not assignable to type '[string, typeof BootstrapLaunch]'.
    Type '[string, typeof BootstrapWelcome]' is not assignable to type '[string, typeof BootstrapLaunch]'.
      Type 'typeof BootstrapWelcome' is not assignable to type 'typeof BootstrapLaunch'.
        Type 'BootstrapWelcome' is not assignable to type 'BootstrapLaunch'.
          Types of property 'componentDidMount' are incompatible.
            Type '(() => void) | undefined' is not assignable to type '() => void'.
              Type 'undefined' is not assignable to type '() => void'.

是Typescript错误还是我做错了什么？

Answer 1

TypeScript试图推断您的值的类型，但是由于您的组件在实现componentDidMount方面有所不同，因此它试图警告您可能的编程错误。

由于所需的值类型比提供的组件的类型宽，因此您可以使用类型参数告诉TypeScript您的意图是什么

public constructor() {
    this.screensMap = new Map<string, ComponentType<any>>([
        [BootstrapLaunch.name, BootstrapLaunch],
        [BootstrapWelcome.name, BootstrapWelcome],
    ]);
}

使用Typescript中的数组初始化Map：new Map（[[k1，v1]，[k2，v2]]）

1 个答案: