如何在 Node.js 中通过击键打破函数内的无限循环？

Question

I have an async function, stopwatch . Upon calling, it starts to print time elapsed (in seconds) on every second.

How can I break this infinite loop and return time elapsed on keystroke ?

async function stopwatch() {
  let elapsed = 0;
  while (true) {
    process.stdout.write(`Elapsed: ${elapsed} seconds`);
    await sleep(1000);
    elapsed++;
    process.stdout.write("\u001b[2K\u001b[0E"); // clear current line and print at this line again next time
  }
  // on Keystroke: return time elapsed
}

export async function sleep(ms) {
  return new Promise((resolve) => setTimeout(resolve, ms));
}

Answer 1

After learning a bit about EventEmitter and with the keypress package suggested by @rksh1997 , I come up with this solution:

const EventEmitter = require("events");
let keypress = require("keypress");

function sleep(ms) {
  return new Promise((resolve) => setTimeout(resolve, ms));
}

class StopWatch extends EventEmitter {
  constructor() {
    super();
    this.elapsed = 0;
  }
  print() {
    process.stdout.write("\u001b[2K\u001b[0E");
    process.stdout.write(this.elapsed.toString());
  }
}

async function runStopWatch(stopWatch) {
  for (;;) {
    if (stopWatch.stopped) break;
    stopWatch.emit("tick");
    await sleep(1000);
  }
}

async function main() {
  let stopWatch = new StopWatch(400);
  stopWatch.on("tick", function () {
    this.elapsed++;
    this.print();
  });
  stopWatch.on("stop", function () {
    this.stopped = true;
  });
  runStopWatch(stopWatch);
  keypress(process.stdin);
  process.stdin.on("keypress", function (ch, key) {
    if (key && key.name == "q") { // hit 'q' to exit
      stopWatch.emit("stop");
      console.log("Elapsed:", stopWatch.elapsed);
      process.stdin.pause();
    }
  });
  process.stdin.setRawMode(true);
  process.stdin.resume();
}

main()

How can I simplify my answer? Is it possible to do this without using the EventEmitter?