How to wait for node exec response?

Question

how can I use a callback tor a promise correctly to get the result from a node exec in the condole.log() function?

import { exec } from 'child_process';
const check = () => {
    exec(`...`, (err, stdout) => {
        if (err) {
         return false         
        }
        else {
         return true
        }
    })
}
console.log(check()) // getting undefined

I've tried using .on('exit') but none worked... would love to get some help here. THANKS!!

Answer 1

You can either use the Promise constructor to do it yourself or you can use the util module to convert a callback invoking function into one that returns a promise

Using the util module

const util = require("util");
const exec = util.promisify(require("child_process").exec);

const check = async () => {
  const output = await exec(`echo hi`);

  console.log(output);
};

check();

Wrapping with the Promise constructor

import { exec } from "child_process";
const check = async () => {
  return new Promise((resolve, reject) => {
    exec(`echo hi`, (err, stdout) => {
      if (err) {
        reject(err);
      } else {
        resolve(stdout);
      }
    });
  });
};