将 class 定义作为参数传递并在 TypeScript 中引用静态成员

Question

我试图将 class 定义作为参数传递给函数，然后在函数内部访问 class 的静态成员，但 Typescript 说静态属性该类型不存在，并询问我是否要访问静态成员。我知道，但无法弄清楚如何以允许的方式指定参数的类型。感觉这应该很简单，我只是遗漏了一些小细节，但是它是什么？

代码示例，引用 this library:

import Web3 from 'web3';

//With a first param typed Web3 regardless of name, Typescript throws an error:
//Property 'providers' does not exist on type 'Web3'.
//Did you mean to access the static member 'Web3.providers' instead?ts(2576)
const getWebSocketProvider = function(
        Web3ClassDefinition: Web3, 
        host: string, 
        port: string
    ) {
    //Custom options and other components motivating use of a wrapper function
    //are removed for this minimal example.
    //Adding .constructor just before .providers changes the error to
    //"Property 'providers' does not exist on type 'Function'.ts(2339)"
    //Adding .prototype.constructor just before .providers changes the error to
    //"Property 'prototype' does not exist on type 'Web3'.ts(2339)"
    return new Web3ClassDefinition.prototype.constructor.providers.WebsocketProvider(
        'wss://'+host+':'+port
    );
};

//This call also has an error:
//Argument of type 'typeof Web3' is not assignable to parameter of type 'Web3'.
//Type 'typeof Web3' is missing the following properties from type 'Web3':
//defaultAccount, defaultBlock, currentProvider, setProvider, and 5 more.ts(2345)
// solves that, 
//but then the main error changes to
//"Property 'providers' does not exist on type Constructor<Web3>."
getWebSocketProvider(Web3, '123.45.67.89', '1234');

请注意，GPL 许可库 (index.d.ts) 中的类型定义包括静态 providers 成员：

export default class Web3 {
    constructor();
    constructor(provider: provider);
    constructor(provider: provider, net: net.Socket);
    //...
    static readonly providers: Providers;
    //...
}

Answer 1

问题是类型 Web3 表示 Web3 class 的实例而不是 class 本身。要将 class 本身作为参数传递，您需要使用类型 typeof Web3。这也是有点神秘的类型错误试图传达的内容：Argument of type 'typeof Web3' (i.e. actual parameter Web3) is not assignable to parameter of type 'Web3' (i.e. formal parameter Web3ClassDefinition).

如果将 Web3ClassDefinition 的类型更改为 typeof Web3，并删除 .prototype.constructor 部分，代码类型检查：

const getWebSocketProvider = function(
        Web3ClassDefinition: typeof Web3, 
        host: string, 
        port: string
    ) {
    return new Web3ClassDefinition.providers.WebsocketProvider(
        'wss://'+host+':'+port
    );
};

TypeScript playground

将 class 定义作为参数传递并在 TypeScript 中引用静态成员

Pass class definition as parameter & reference static member in TypeScript

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