Node.js - MaxListenersExceededWarning - 使用 readline 模块编写 Node.js CLI 应用程序时

Question

我正在尝试在循环中不断添加数字，如下面的代码所示：

const readline = require('readline');

const askOnCommandLine = (question) =>
  new Promise((resolve) => {
    const p = readline.createInterface({
      input: process.stdin,
      output: process.stdout,
      prompt: question,
    });

    p.on('line', (input) => {
      resolve(input);
    });

    p.prompt();
  });

let counter = 0;

(async () => {
  while (true) {
    console.log('Loop:', counter);
    const number1 = await askOnCommandLine('Enter 1st number: ');
    const number2 = await askOnCommandLine('Enter 2nd number: ');
    console.log('Addition:', parseInt(number1) + parseInt(number2));
    counter += 1;
  }
})();

但是这里有两个问题：

1. 它会多次打印单个按键，如屏幕截图所示。

1. 循环几次后，出现如下错误：

Enter 2nd number:
(node:706492) MaxListenersExceededWarning: Possible EventEmitter memory leak detected.
11 end listeners added to [ReadStream]. Use emitter.setMaxListeners() to increase limit
(Use `node --trace-warnings ...` to show where the warning was created)

Answer 1

就像浏览器中的事件侦听器一样，在处理完这些流接口后，您需要处理它们，否则它们只会在内存中不断累积（因此会出现警告和意外行为）。看起来readline 公开了一个close() 方法，为什么不在完成后关闭流？

const askOnCommandLine = (question) =>
  new Promise((resolve) => {
    const p = readline.createInterface({
      input: process.stdin,
      output: process.stdout,
      prompt: question,
    });

    p.on('line', (input) => {
      resolve(input);
      p.close();
    });

    p.prompt();
  });