denoland-deno/std/ws/example_client.ts

import {
  connectWebSocket,
  isWebSocketCloseEvent,
  isWebSocketPingEvent,
  isWebSocketPongEvent,
} from "../ws/mod.ts";
import { encode } from "../encoding/utf8.ts";
import { BufReader } from "../io/bufio.ts";
import { TextProtoReader } from "../textproto/mod.ts";
import { blue, green, red, yellow } from "../fmt/colors.ts";

const endpoint = Deno.args[0] || "ws://127.0.0.1:8080";
/** simple websocket cli */
try {
  const sock = await connectWebSocket(endpoint);
  console.log(green("ws connected! (type 'close' to quit)"));

  const messages = async (): Promise<void> => {
    for await (const msg of sock) {
      if (typeof msg === "string") {
        console.log(yellow(`< ${msg}`));
      } else if (isWebSocketPingEvent(msg)) {
        console.log(blue("< ping"));
      } else if (isWebSocketPongEvent(msg)) {
        console.log(blue("< pong"));
      } else if (isWebSocketCloseEvent(msg)) {
        console.log(red(`closed: code=${msg.code}, reason=${msg.reason}`));
      }
    }
  };

  const cli = async (): Promise<void> => {
    const tpr = new TextProtoReader(new BufReader(Deno.stdin));
    while (true) {
      await Deno.stdout.write(encode("> "));
      const line = await tpr.readLine();
      if (line === null) {
        break;
      }
      if (line === "close") {
        break;
      } else if (line === "ping") {
        await sock.ping();
      } else {
        await sock.send(line);
      }
    }
  };

  await Promise.race([messages(), cli()]).catch(console.error);

  if (!sock.isClosed) {
    await sock.close(1000).catch(console.error);
  }
} catch (err) {
  console.error(red(`Could not connect to WebSocket: '${err}'`));
}

Deno.exit(0);