Node.js 和 Typescript，如何动态访问导入的模块

Question

我正在努力在 TypeScript 中创建一个不和谐的机器人。我想创建一个通用的命令调度程序，这是我到目前为止的工作：

app.ts：

import * as Discord from 'discord.js';
import * as config from '../config'
import * as commands from './Commands/index'

const token : string = config.Token;

const _client = new Discord.Client();

_client.on('message', (msg) => {
    let args : Array<string> = msg.content.split(' ')
    let command : string = args.shift() || " ";

    if(!command.startsWith("!")) return;
    else{
        commands[`${command.toLower().substring(1)}`]
    }

})

命令/索引.ts

export {default as ping} from './ping';
export {default as prong} from './prong';

Ping.ts：所有命令的结构相同

import { Message } from "discord.js";

export default {
    name : 'ping',
    description: 'Ping!',
    execute(message: Message, args: Array<string>){
        message.channel.send('Pong.');
    }
}

在索引命令导入时，我可以使用以下命令成功调用正确的执行函数：

commands['pong'].execute()

但是，当尝试像这样动态索引它时：

commands[command].execute()

我收到以下错误：

Element implicitly has an 'any' type because expression of type 'string' can't be used to index type 'typeof import("c:/Users/alexs/Desktop/Discord Bot/src/Commands/index")'. No index signature with a parameter of type 'string' was found on type 'typeof import("c:/Users/alexs/Desktop/Discord Bot/src/Commands/index")'

无论如何我可以将命令导入类型转换为某种对象或集合吗？如果没有，有没有办法我可以创建某种访问器来完成这项工作？我是打字稿的新手，很好奇有什么可能。

Answer 1

我为您的命令建议一种不同的方法，这种方法可以解决两件事：

• 别忘了正确导出文件
• 您会收到类型安全的命令

让我们首先为你的命令创建一个接口，这个接口描述元数据，你想添加多少就添加多少

export interface Command {
  name: string
  description: string
  // Making `args` optional
  execute(message: Message, args?: string[]) => any
}

现在您已经为命令设置了形状，让我们确保您的所有命令都具有正确的形状

import { Command } from "./types"

// This will complain if you don't provide the right types for each property
const command: Command = {
  name: "ping",
  description: "Ping!",
  execute(message: Message, args: string[]) => {
    message.channel.send("Pong")
  }
}

export = command

下一部分是加载你的命令，discord.js 有 glob 作为依赖项，它可以帮助你轻松读取目录中的文件，让我们使用一些实用程序，这样我们就可以很好地使用 async / await

import glob from "glob" // included by discord.js
import { promisify } from "util" // Included by default
import { Command } from "./types"

// Make `glob` return a promise
const globPromise = promisify(glob)

const commands: Command = []

client.once("ready", async () => {
  // Load all JavaScript / TypeScript files so it works properly after compiling
  // Replace `test` with "await globPromise(`${__dirname}/commands/*.{.js,.ts}`)"
  // I just did this to fix SO's syntax highlighting!
  const commandFiles = test

  for (const file of commandFiles) {
    // I am not sure if this works, you could go for require(file) as well
    const command = await import(file) as Command
    commands.push(command)
  }
})

const prefix = "!"

client.on("message", message => {
  // Prevent the bot from replying to itself or other bots
  if (message.author.bot) {
    return
  }

  const [commandName, ...args] = message.content
    .slice(prefix.length)
    .split(/ +/)

  const command = commands.find(c => c.name === commandName)

  if (command) {
    command.execute(message, args)
  }
})

我希望这能给你一个好的起点，并向你展示 TypeScript 的力量

Answer 2

你可以导入类型，然后像这样进行转换

commands[command as Type].execute();