javascript - 等待在 while 循环中不工作

Question

我的应用代码:

const readline = require('readline');

const rl = readline.createInterface({
  input: process.stdin,
  output: process.stdout
});
async function init() {
  while (true) {
  console.log("TICK");
  await (rl.question('What do you think of Node.js? ', await (answer) => {

       console.log('Thank you for your valuable feedback:', answer);



  rl.close();
  }))
  await new Promise(resolve => setTimeout(resolve, 1000))
 }
}

它必须如何工作(或者我认为它应该如何工作):

当我们遇到 await (rl.question('... 它应该等待响应(用户输入)并且只比循环继续。

实际运作方式

当它遇到 await new Promise(resolve => setTimeout(resolve, 1000)) 时它正在工作，但是 await (rl.question('... 你获取输出但代码继续执行而不等待用户输入。

Answer 1

async 函数需要一个返回 promise 的函数。 rl.question 不返回 promise ；它需要回调。所以你不能只是把 async 放在它前面，希望它能工作。

您可以通过将其包装在一个 promise 中使其工作，但这可能比它值得的工作更多:

const readline = require('readline');

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

function rl_promise(q) {
    return new Promise(resolve => {
        rl.question('What do you think of Node.js? ', (answer) => {
            resolve('Thank you for your valuable feedback:', answer)
        })
    })
}
async function init() {
    while (true) {
        console.log("TICK");
        let answer = await rl_promise('What do you think of Node.js? ')
        console.log(answer)
    }
    rl.close();
}

init()

话虽如此，更好的方法是避免 while 循环并设置停止条件。例如，当用户键入“退出”时。我认为这更简单也更容易理解:

const readline = require('readline');

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

function ask() {   
    rl.question('What do you think of Node.js? ', (answer) => {
        console.log('Thank you for your valuable feedback:', answer);
        if (answer != 'quit') ask()
        else  rl.close();
        })
}   

ask()