javascript - 如何使用nodejs readline库通过返回函数从stdin读取

Question

var readline = require('readline');
var reader = readline.createInterface({
  input: process.stdin,
  output: process.stdout,
  terminal: false
});
function stdinput(){
    reader.on('line', function (cmd) {
        return cmd;
      });
}
console.log(stdinput());

输出:

undefined

stdinput() 函数在从 stdin 读取输入之前给出“未定义”。 我搜索了很多资源，但无法理解为什么它是异步解释的。

I am writing CLI interactive application in nodejs. it reads input many times. If we use recursion to read, it takes more stack memory and If we use callbacks, Promise and Async/await here also getting undefined before stdinput() i.e below part of the code is executing first before reading input.

Answer 1

或者您可以使用回调:

var readline = require('readline');
var reader = readline.createInterface({
  input: process.stdin,
  output: process.stdout,
  terminal: false
});

function stdinput(callback){
    reader.on('line', function (cmd) {
        callback (cmd);
      }); 
}

stdinput(function (cmd) {
    console.log('cmd: ', cmd); 
});