Handling child process errors in Node.js - Interactive Code Practice

Practice - 5 Tasks

1fill in blank

easy

Complete the code to import the child_process module.

Node.js

const { exec } = require('[1]');

Drag options to blanks, or click blank then click option'

Afs

Bchild_process

Chttp

Dpath

Attempts:

3 left

💡 Hint

Common Mistakes

Using unrelated modules like 'fs' or 'http'.

Misspelling the module name.

The child_process module is used to create and control child processes in Node.js.

2fill in blank

medium

Complete the code to execute a shell command using exec.

Node.js

exec('ls -l', (error, stdout, stderr) => {
  if ([1]) {
    console.error(`Error: ${error.message}`);
    return;
  }
  console.log(stdout);
});

Drag options to blanks, or click blank then click option'

Aerror

Bstdout

Cstderr

Dnull

Attempts:

3 left

💡 Hint

Common Mistakes

Checking stdout or stderr instead of error.

Ignoring the error argument.

The error argument indicates if the command failed. Checking it helps handle errors.

3fill in blank

hard

Fix the error in the code to properly listen for the 'error' event on a child process.

Node.js

const child = exec('node someScript.js');
child.on('[1]', (err) => {
  console.error('Child process error:', err);
});

Drag options to blanks, or click blank then click option'

Aerror

Bexit

Cclose

Ddisconnect

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'exit' or 'close' events to catch errors.

Not attaching an error listener.

The 'error' event is emitted when the child process fails to start or has an error.

4fill in blank

hard

Fill both blanks to handle errors and output from a spawned child process.

Node.js

const { spawn } = require('child_process');
const child = spawn('ls', ['-l']);
child.stdout.on('[1]', (data) => {
  console.log(`Output: ${data}`);
});
child.on('[2]', (err) => {
  console.error(`Error: ${err.message}`);
});

Drag options to blanks, or click blank then click option'

Adata

Berror

Cclose

Dexit

Attempts:

3 left

💡 Hint

Common Mistakes

Using 'close' or 'exit' to get output data.

Not listening to the 'error' event.

The 'data' event on stdout streams output, and 'error' event handles errors.

5fill in blank

hard

Fill all three blanks to create a child process, handle errors, and print output correctly.

Node.js

import { exec } from 'child_process';

exec('node -v', ([1], [2], [3]) => {
  if ([1]) {
    console.error(`Execution error: $[1].message}`);
    return;
  }
  console.log(`Node version: $[2]`);
});

Drag options to blanks, or click blank then click option'

Aerror

Bstdout

Cstderr

Dresult

Attempts:

3 left

💡 Hint

Common Mistakes

Mixing up the order of parameters.

Ignoring the error parameter.

The callback parameters are error, stdout, and stderr. We check error first, then print stdout.