path.parse and path.format in Node.js - Practice Problems & Coding Challenges

Challenge - 5 Problems

❓ Predict Output

intermediate

Output of path.parse on a Windows path

What is the output of the following Node.js code using path.parse on a Windows-style path?

Node.js

import path from 'path';
const parsed = path.parse('C:\\Users\\Alice\\Documents\\file.txt');
console.log(parsed);

A { root: 'C:', dir: 'C:\\Users\\Alice\\Documents', base: 'file.txt', ext: '.txt', name: 'file' }

B { root: 'C:\\', dir: 'C:\\Users\\Alice\\Documents', base: 'file.txt', ext: '.txt', name: 'file' }

C { root: 'C:\\Users\\Alice\\Documents', dir: 'C:\\Users\\Alice', base: 'file.txt', ext: '.txt', name: 'file' }

D { root: '', dir: 'C:\\Users\\Alice\\Documents', base: 'file.txt', ext: '.txt', name: 'file' }

💡 Hint

Remember that on Windows, the root includes the drive letter and backslash.

The path.parse method splits the path into root, dir, base, ext, and name. On Windows, the root includes the drive letter and backslash, so root is 'C:\\'. The directory is everything before the base file name.

❓ Predict Output

intermediate

Result of path.format from a parsed object

Given the parsed path object below, what is the output of path.format?

Node.js

import path from 'path';
const parsed = {
  root: '/',
  dir: '/home/user/docs',
  base: 'notes.txt',
  ext: '.txt',
  name: 'notes'
};
console.log(path.format(parsed));

A /notes.txt

B /home/user/docs/.txt

C /home/user/docs/notes.txt

D /home/user/docs/notes

💡 Hint

The base property takes priority over name and ext when formatting.

The path.format method constructs a path string from the object. If base is provided, it uses that directly as the file name, ignoring name and ext. The directory is combined with the base.

❓ component_behavior

advanced

Effect of missing properties in path.format input

What will path.format output if the input object has only name and ext properties, but no dir or root?

Node.js

import path from 'path';
const obj = { name: 'image', ext: '.png' };
console.log(path.format(obj));

A image.png

B /image.png

C .png

D image

💡 Hint

If no directory or root is given, the output is just the file name.

When dir and root are missing, path.format returns just the file name constructed from name and ext. So it returns 'image.png'.

📝 Syntax

advanced

Identify the syntax error in path.parse usage

Which option contains a syntax error when using path.parse in Node.js?

A const parsed = path.parse('/usr/local/bin'

B const parsed = path.parse('/usr/local/bin', true);

C const parsed = path.parse('/usr/local/bin'); console.log(parsed);

D const parsed = path.parse('/usr/local/bin');

💡 Hint

Check for missing parentheses or semicolons.

Option A is missing the closing parenthesis and semicolon, causing a syntax error. The other options are syntactically correct.

🔧 Debug

expert

Why does path.format ignore name and ext when base is present?

Consider this code snippet:

const obj = { dir: '/var/log', base: 'app.log', name: 'app', ext: '.log' };
console.log(path.format(obj));

Why does the output use base and ignore name and ext?

A Because <code>base</code> is empty, so <code>name</code> and <code>ext</code> are ignored.

B Because <code>name</code> and <code>ext</code> are deprecated properties and ignored by <code>path.format</code>.

C Because <code>path.format</code> only uses <code>dir</code> and <code>base</code> and never uses <code>name</code> or <code>ext</code>.

D Because <code>base</code> has higher priority and overrides <code>name</code> and <code>ext</code> when formatting the path.

💡 Hint

Check the priority order of properties in path.format.

The path.format method uses base if it exists, ignoring name and ext. This is by design to avoid ambiguity in file naming.