javascript - "While"阻塞异步操作

Question

当我尝试运行该代码时 -

const MagicHomeControl = require("magic-home").Control;
const readlineSync = require("readline-sync");

const light = new MagicHomeControl("192.168.1.77");

let answer;

while(true){
    answer = readlineSync.question("What do you wish to do?\nTurn on - on\nTurn off - off\nQuit the program - quit\n");
    switch(answer){
        case "on":
            light.turnOn(function(err, success){

            });
            break;
        case "off":
            light.turnOff(function(err, success){

            });
            break;
        case "quit":
            process.exit(-1);
            break;
        default:
            console.log("Wrong input, try again");
            break;
    }
}

只有退出选项才能正常工作。但是，如果我编写相同的代码，但没有 while 循环 = 一切正常，但只有一次。有什么想法吗？

Answer 1

在调用turnOn 或turnOff 后，您会立即调用readlineSync.question，这可能会阻止turnOn 背后的API 的任何可能性 或 turnOff 函数来完成，或者至少向 JavaScript 报告。

您可以通过使循环异步来解决这个问题，并且仅在 turnOn 或 turnOff 操作完成时才“迭代”:

(function loop(err, success) {
    if (err) console.log(err);
    const answer = readlineSync.question("What do you wish to do?\nTurn on - on\nTurn off - off\nQuit the program - quit\n");
    switch(answer){
    case "on":
        light.turnOn(loop);
        break;
    case "off":
        light.turnOff(loop);
        break;
    case "quit":
        process.exit(-1);
        break;
    default:
        console.log("Wrong input, try again");
        setTimeout(loop); // Also do this asynchronously to save the stack.
    }
})(); // IIFE - immediately invoked function expression