Node.jsとの違いを感じながらDenoでChatアプリをサクッと作ってみる

$ brew install deno
Updating Homebrew...
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==> Downloading https://homebrew.bintray.com/bottles/deno-1.0.0.mojave.bottle.tar.gz
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==> Summary
🍺  /usr/local/Cellar/deno/1.0.0: 9 files, 42.0MB　<- 軽い

$ deno --version
deno 1.0.0
v8 8.4.300
TypeScript 3.9.2

$ deno run https://deno.land/std/examples/welcome.ts
Download https://deno.land/std/examples/welcome.ts
Warning Implicitly using master branch https://deno.land/std/examples/welcome.ts
Compile https://deno.land/std/examples/welcome.ts
Welcome to Deno 🦕

import { listenAndServe } from "https://deno.land/std/http/server.ts";

listenAndServe({ port: 3000 }, async (req) => {
  if (req.method === "GET" && req.url === "/") {
    req.respond({
      status: 200,
      headers: new Headers({
        "content-type": "text/html",
      }),
      body: await Deno.open("./index.html"),
    });
  }
});

console.log("Server running on localhost:3000");

import { camelCase } from 'https://cdn.pika.dev/camel-case@^4.1.1'

export { camelCase } from "https://cdn.pika.dev/camel-case@^4.1.1";

import { camelCase } from './deps.ts'

error: Uncaught PermissionDenied: network access to "0.0.0.0:3000", run again with the --allow-net flag
    at unwrapResponse ($deno$/ops/dispatch_json.ts:43:11)
    at Object.sendSync ($deno$/ops/dispatch_json.ts:72:10)
    at Object.listen ($deno$/ops/net.ts:51:10)
    at listen ($deno$/net.ts:152:22)
    at serve (https://deno.land/std/http/server.ts:261:20)
    at listenAndServe (https://deno.land/std/http/server.ts:28

$ deno run --allow-net --allow-read server.ts
Compile file:///Users/shokokashiwagi/deno-chat/server.ts
Server running on localhost:3000

import {
  WebSocket,
  isWebSocketCloseEvent,
} from "https://deno.land/std/ws/mod.ts";
import { v4 } from "https://deno.land/std/uuid/mod.ts";

const users = new Map<string, WebSocket>();

function broadcast(message: string, senderId?: string): void {
  if (!message) return;
  for (const user of users.values()) {
    user.send(senderId ? `[${senderId}]: ${message}` : message);
  }
}

export async function chat(ws: WebSocket): Promise<void> {
  const userId = v4.generate();

  // Register user connection
  users.set(userId, ws);
  broadcast(`> User with the id ${userId} is connected`);

  // Wait for new messages
  for await (const event of ws) {
    const message = typeof event === "string" ? event : "";
    broadcast(message, userId);
    // Unregister user conection
    if (!message && isWebSocketCloseEvent(event)) {
      users.delete(userId);
      broadcast(`> User with the id ${userId} is disconnected`);
      break;
    }
  }
}

deno run -c tsconfig.json [ファイル名]

import { assertStrictEq } from "https://deno.land/std/testing/asserts.ts"; //アサート機能も標準ライブラリに実装されてます
import { camelize } from "./camelize.ts";

Deno.test("camelize works", async () => {
  assertStrictEq(camelize("this is an example"), "thisIsAnExample 🐪🐪🐪");
});

$ deno test
Compile file:///Users/shokokashiwagi/deno-chat/camelize.ts
running 1 tests
test camelize works ... ok (6ms)

test result: ok. 1 passed; 0 failed; 0 ignored; 0 measured; 0 filtered out (6ms)