https://rcoedo.com/blog/2018/08/27/mastering-the-node-js-repl-part-three

Examples for "Mastering the Node.js REPL, Part Three"

This gist contains the examples for the article "Mastering the Node.js REPL, Part Three".

- https://medium.com/trabe/mastering-the-node-js-repl-part-3-c0374be0d1bf
- https://rcoedo.com/blog/2018/08/27/mastering-the-node-js-repl-part-three

main.js

const express = require("express");
const controllers = require("./controllers");

const app = express();

app.get("/users", controllers.getUsers);
app.get("/users/:userId", controllers.getUser);
app.get("/users/:userId/posts", controllers.getUserPosts);

app.get("/posts", controllers.getPosts);
app.get("/posts/:postId", controllers.getPost);

app.listen(3000, () => console.log("express server listening on port 3000"));

package-2.json

"scripts": {
  "start": "nodemon main.js",
  "repl": "./bin/repl-client localhost:3001"
}

package.json

"scripts": {
  "start": "nodemon main.js",
  "repl": "node dev/repl/repl.js"
}

repl-client.js

#!/usr/bin/env node
const net = require("net");

const args = process.argv.slice(2);
if (args.length < 1) {
  console.log("USAGE: repl <HOST:PORT>");
  process.exit(1);
}

const url = args[0];
const [host, port] = url.split(":");

const socket = net.connect(parseInt(port), host);

process.stdin.pipe(socket);
socket.pipe(process.stdout);

socket.on("connect", () => {
  process.stdin.setRawMode(true);
});

socket.on("close", () => {
  process.exit(0);
});

process.on("exit", () => {
  socket.end();
});

repl-server-fn.js

const start = socket => {
  console.log("repl client connected");
  sayWelcome(socket);

  const repl = Repl.start({
    prompt,
    input: socket,
    output: socket,
    terminal: true,
  });

  // define commands...
  // initialize context...
  // listen repl events...

  socket.on("error", e => {
    console.log(`repl socket error: ${e}`);
  });

  repl.on("exit", () => {
    console.log("repl client disconnected");
    socket.end();
  });
};

repl-server.js

const net = require("net");
const repl = require("./repl");

const server = net.createServer(socket => {
  start(socket);
});

module.exports = server;

repl.js

const Repl = require("repl");
const { extendWith, colorize, defineCommands, clearRequireCache } = require("./utils");
const { sayWelcome, sayBye, sayDoc, prompt } = require("./cli");

// Define a context initializer
const initializeContext = context => {
  clearRequireCache();

  extendWith({
    R: require("ramda"),
    services: require("../../services"),
  })(context);
};

sayWelcome();

const repl = Repl.start({ prompt });

defineCommands({
  doc: {
    help: "Get information about the loaded modules",
    action() {
      this.clearBufferedCommand();
      sayDoc();
      this.displayPrompt();
    },
  },
})(repl);

initializeContext(repl.context);

repl.on("reset", initializeContext);
repl.on("exit", sayBye);