typescript - 如何根据接口检查类的静态属性

Question

JavaScript中的这个构造函数：

function C() {
    this.x = 100;
}
C.prototype = {
    constructor: C,
    m() {}
};
C.staticM = function () {};

我已经在 TypeScript 中进行了转换：

class C {
    x: number;

    constructor() {
        this.x = 100;
    }

    m() {}
    static staticM() {}
}

我还添加了这些接口C()：

interface CConstructor {
    new (): CInstance;
    staticM(): void;
}

interface CPrototype {
    constructor: CConstructor;
    m(): void;
}

interface CInstance extends CPrototype {
    x: number;
}

但是当我写：

class C implements CInstance {...}

我收到错误消息：

[ts]
Class 'C' incorrectly implements interface 'CInstance'.
Types of property 'constructor' are incompatible.
    Type 'Function' is not assignable to type 'CConstructor'.
    Property 'staticM' is missing in type 'Function'.

如何根据staticM()接口检查类的静态属性（在我的示例中）？

标签： typescript

Answer 1

您不能拥有接口的静态实现。当您将类分配给接口的类型化变量时，您可以得到该类满足接口的事实：

class C {
    x: number;

    constructor() {
        this.x = 100;
    }

    m() {}
    static staticM() {}
}

interface CConstructor {
    new (): CInstance;
    staticM(): void;
}

interface CInstance {
    x: number;
    m(): void;
}

let check: CConstructor = C; //error here if implementation is incorrect

或者类似地，您可以使用一个函数来创建将检查实现是否符合接口的类

function declareC(cls: CConstructor) {
    return cls;
}


const C = declareC(class {
    x: number;

    constructor() {
        this.x = 100;
    }

    m() { }
    static staticM() { }
});
type C =InstanceType<typeof C>

interface CConstructor {
    new(): CInstance;
    staticM(): void;
}

interface CInstance {
    x: number;
    m(): void;
}