承诺中的 Node.js readline

Question

我正在尝试使用 node.js 包 readline 在命令行上获取用户输入，并且我想通过 Promise 管道输入的输入。但是，输入永远不会通过 then 链。我认为问题可能出在回调方法中实现了承诺，但我不知道如何解决该问题。

这个问题的一个例子如下所示：

import rlp = require('readline');

const rl = rlp.createInterface({
    input: process.stdin,
    output: process.stdout
  });  

let prom = new Promise((fulfill, reject) => {
    rl.question('Enter input: ', input => rl.close() && fulfill(input));
});

prom.then(result => {console.log(result); return prom})
    .then(result => {console.log(result); return prom})
    .then(result => console.log(result));

如果在node.js中运行，问题会出现一次，输入后程序就停止了。我希望它等到输入第一个输入，然后它应该打印这个输入并请求下一个输入。

提前致谢！

Answer 1

一旦你的承诺得到解决，再等待是没有用的。我还将 rl.close() 调用移到了末尾，因为它只需要调用一次。

const rlp = require('readline');

const rl = rlp.createInterface({
        input: process.stdin,
        output: process.stdout

});

function ask() {
    return new Promise((resolve, reject) => {
        rl.question('Enter input: ', (input) => resolve(input) );
    });
}

ask()
.then((result) => { console.log(result); return ask(); })
.then((result) => { console.log(result); return ask(); })
.then(result => { console.log(result); rl.close() });

Answer 2

这是here这个问题的答案，我不值得称赞。

// Function
function Ask(query) {
  const readline = require("readline").createInterface({
    input: process.stdin,
    output: process.stdout
  })

  return  new Promise(resolve => readline.question(query, ans => {
  readline.close();
  resolve(ans);
}))
}

 
// example useage
async function main() {

 var name = await Ask("whats you name")
 console.log(`nice to meet you ${name}`)

 var age = await Ask("How old are you?")
 console.log(`Wow what a fantastic age, imagine just being ${age}`)
}

main()

Answer 3

const readline = require('readline');

const rl = readline.createInterface({ input: process.stdin, output: process.stdout });
const ask = (query) => new Promise((resolve) => rl.question(query, resolve));

ask('A: ').then(async (a) => {
  const b = await ask('B: ');
  const c = await ask('B: ');

  console.log(a, b, c);

  rl.close();
});

rl.on('close', () => process.exit(0));

Answer 4

Node.js 17 is here with new promise-based APIs for readline module:

import * as readline from 'node:readline/promises'
import { stdin as input, stdout as output } from 'process'

const rl = readline.createInterface({input, output})

const answer = await rl.question('What do you think of Node.js? ')

console.log(`Thank you for your valuable feedback: ${answer}`)

rl.close()

https://nodejs.org/api/readline.html#readline

Answer 5

节点提示.mjs

import { createInterface as createQuestionInterface } from 'readline';

const rl = createQuestionInterface({
  input: process.stdin,
  output: process.stdout
});

function questionLine(multiline, resolve, i, input, rl) {
  if (!multiline) {
    resolve(i);
  } else {
    if (input && !i) {
      resolve(input);
    } else {
      return input + i + "\r\n";
    }
  }
  return input;
}

function promptMultiLine(questionText) { // This is async by returning promise
  return prompt(questionText, true);
}

async function prompt(questionText, multiline = false) {
  return await (new Promise((resolve, reject) => {
    let input = '';
    rl.question(`${questionText}: `, (i) => {
      input = questionLine(multiline, resolve, i, input, rl);
    });
    rl.on('line', (i) => {
      input = questionLine(multiline, resolve, i, input, rl);
    });
  }));
}

async function run() {
  const question = prompt("please enter response [enter to complete]");
  console.log(question);
  const questionMultiLine = promptMultiLine("please enter response [enter text and enter twice]");
  console.log(questionMultiLine);
}

run();