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用Typescript中的数组初始化映射:新映射([[k1,v1],[k2,v2]]

typescript

2

alexojegu · 技术社区 · 7 年前

这很好用:

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

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

但这是失败的:

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

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

下一个错误是:

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'.

1 回复 | 直到 7 年前

1

0

Karol Majewski 7 年前

TypeScript试图推断值的类型,但由于组件在实现方面不同 componentDidMount ,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类型更广泛,因此可以使用类型参数告诉TypeScript您的意图:

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