等待来自 readline 模块（Node.Js）的用户输入

Question

我正在创建一个模块来获得经验并缩短一些代码。我有一段以简化方式使用 readline 的代码，例如var x = arkin.question("How old are you? ");。 Readline 不等待答案。它产生这个：

你几岁了？未定义

代码：

const readline = require('readline');

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

exports.question = function(q){

  var response;

  rl.setPrompt(q);
  rl.prompt();
  rl.on('line', (userInput) => {
    response = userInput;
    rl.close();
  });

  rl.on('close', () => {
    return response;
  });
}

我这样称呼它：

var age = arkin.question("How old are you? ");
console.log(age);

我已尝试使用此代码：

rl.question(q, (userInput) => {
    rl.close;
    response = userInput;
    return response;
});

但我得到了相同的结果。提前感谢您的帮助。

Answer 1

每当您调用 arki.question 时，它都会注册事件侦听器 .on("line") 和 .on("close") 然后从函数返回。无论您从 .on("close") 事件侦听器question 函数返回什么，都不知道它，因为它不再在调用堆栈上。您可以使用回调或带有async...await 的承诺来获得结果。

带有回调

const readline = require('readline');

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

exports.question = function(q , cb ){

    var response;

    rl.setPrompt(q);
    rl.prompt();

    rl.on('line', (userInput) => {
        response = userInput;
        rl.close();
    });

    rl.on('close', () => {
        return cb(response);
    });
};

你这样称呼它

var age  = arki.question("how old are you? ", resp => {
    console.log(resp);
});

承诺

const readline = require('readline');

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

exports.question = function(q){

    var response;

    rl.setPrompt(q);
    rl.prompt();

    return new Promise(( resolve , reject) => {

        rl.on('line', (userInput) => {
            response = userInput;
            rl.close();
        });

        rl.on('close', () => {
            resolve(response);
        });

    });


};

你这样称呼它

arki.question("how old are you? ").then( response => console.log(response) );

或

; ( async () => {
    console.log(await arki.question("how old are you? "));
})();

Answer 2

//global stuff, where we import readline. 
//But avoid assigning global vars.
    var age;
    var readline = require('readline'), menu;
        
//define function
    function whatever() = {
    
//create readline instance and assign it to menu
    menu = readline.createInterface({
        input: process.stdin,
        output: process.stdout
    });
        
//Use the readline.question method, which is what you're looking for.
//It requires a callback function with a variable for the users input.
    menu.question('How old are you? ', function(input) {
        age = input;
    });
        
    console.log(`You are ${age} years old.`);
}
        
//Tell node to run the program
whatever();