path.parse and path.format in Node.js - Cheat Sheet & Quick Revision

Recall & Review

beginner

What does path.parse() do in Node.js?

path.parse() takes a file path string and breaks it into an object with parts like root, dir, base, ext, and name. It helps you understand or use each part separately.

beginner

What are the main properties returned by path.parse()?

The main properties are:

• root: The root of the path (like '/' or 'C:\\')
• dir: The directory path without the file
• base: The file name with extension
• ext: The file extension (like '.txt')
• name: The file name without extension

beginner

What does path.format() do in Node.js?

path.format() takes an object with path parts (like dir, base, name, ext) and combines them into a full path string. It's like putting puzzle pieces back together.

intermediate

How do path.parse() and path.format() work together?

You can use path.parse() to split a path into parts, change or inspect those parts, then use path.format() to build a new path string from the parts. It's like breaking a sentence into words, changing a word, then joining it back.

beginner

If you have { dir: '/home/user', base: 'file.txt' }, what will path.format() return?

It will return the string '/home/user/file.txt'. It joins the directory and the base file name into a full path.

Which method breaks a file path into parts like root, dir, base, ext, and name?

A path.parse()

B path.format()

C path.join()

D path.resolve()

path.parse() splits a path string into its parts.

Which method combines parts of a path object into a full path string?

A path.parse()

B path.format()

C path.basename()

D path.dirname()

path.format() builds a path string from an object with path parts.

What property in the object returned by path.parse() contains the file extension?

A name

B base

C ext

D dir

The ext property holds the file extension, like '.txt'.

If you want to change the file name but keep the directory, which method helps you split the path first?

A path.format()

B path.extname()

C path.join()

D path.parse()

path.parse() splits the path so you can change parts like the file name.

Given { root: '/', dir: '/home/user', base: 'file.txt', ext: '.txt', name: 'file' }, what will path.format() return?

A /home/user/file.txt

B /file.txt

C /home/user/file

D file.txt

path.format() combines the parts into the full path string.

Explain how you can use path.parse() and path.format() together to rename a file in a path.

Think about breaking the path, changing the file name, then joining it back.

Describe the difference between the base and name properties in the object returned by path.parse().

One includes the extension, the other does not.

Practice

1. What does path.parse do in Node.js?

easy

A. It breaks a file path into parts like root, dir, base, name, and ext.

B. It combines multiple file paths into one string.

C. It reads the contents of a file at the given path.

D. It deletes a file at the specified path.

Solution

1. Step 1: Understand the purpose of path.parse

   path.parse takes a file path string and splits it into an object with properties like root, dir, base, name, and ext.

2. Step 2: Compare with other options

   Options A, C, and D describe different file system operations, not path parsing.

3. Final Answer:

   It breaks a file path into parts like root, dir, base, name, and ext. -> Option A

4. Quick Check:

   path.parse splits path into parts [OK]

Hint: Remember: parse means split path into pieces [OK]

Common Mistakes:

• Confusing path.parse with reading file contents
• Thinking path.parse combines paths
• Mixing up path.parse with deleting files

2. Which of the following is the correct way to use path.format to build a path from parts?

easy

A. path.format('file.txt')

B. path.format('/home/user/file.txt')

C. path.format({ root: '/', dir: '/home/user', base: 'file.txt' })

D. path.format(['home', 'user', 'file.txt'])

Solution

1. Step 1: Identify correct argument type for path.format

   path.format expects an object with path parts like root, dir, base, name, or ext.

2. Step 2: Check each option

   path.format({ root: '/', dir: '/home/user', base: 'file.txt' }) correctly passes an object with root, dir, and base. Options B, C, and D pass strings or arrays, which are invalid.

3. Final Answer:

   path.format({ root: '/', dir: '/home/user', base: 'file.txt' }) -> Option C

4. Quick Check:

   path.format needs object with parts [OK]

Hint: path.format needs an object, not a string or array [OK]

Common Mistakes:

• Passing a string instead of an object to path.format
• Using an array instead of an object
• Confusing path.format with path.parse usage

3. What is the output of this code?

const path = require('path');
const parsed = path.parse('/home/user/docs/file.txt');
console.log(parsed.base);

medium

A. '/home/user/docs/file.txt'

B. 'file.txt'

C. 'file'

D. '.txt'

Solution

1. Step 1: Understand what path.parse returns

   path.parse returns an object with properties including base, which is the last part of the path with extension.

2. Step 2: Check the base property for given path

   For '/home/user/docs/file.txt', base is 'file.txt'.

3. Final Answer:

   'file.txt' -> Option B

4. Quick Check:

   parsed.base = 'file.txt' [OK]

Hint: base is filename with extension from path.parse [OK]

Common Mistakes:

• Confusing base with dir or name
• Expecting full path instead of base
• Mixing base with extension only

4. Identify the error in this code snippet:

const path = require('path');
const parts = path.parse('/var/log/sys.log');
const newPath = path.format(parts.dir + '/backup/' + parts.base);
console.log(newPath);

medium

A. path.format expects an object, but a string was passed.

B. path.parse cannot parse absolute paths.

C. The variable parts is not defined.

D. The console.log statement is missing parentheses.

Solution

1. Step 1: Check the argument passed to path.format

   path.format requires an object with path parts, but here a string is passed by concatenating parts.dir, '/backup/', and parts.base.

2. Step 2: Understand correct usage of path.format

   To add '/backup/' folder, modify parts.dir property or create a new object, then pass that object to path.format.

3. Final Answer:

   path.format expects an object, but a string was passed. -> Option A

4. Quick Check:

   path.format needs object, not string [OK]

Hint: path.format always needs an object, never a string [OK]

Common Mistakes:

• Passing a string instead of an object to path.format
• Assuming path.parse fails on absolute paths
• Forgetting parentheses in console.log (not true here)

5. Given this code, what will console.log(newPath) output?

const path = require('path');
const parts = path.parse('/usr/local/bin/node');
const updatedParts = { ...parts, dir: parts.dir + '/backup' };
const newPath = path.format(updatedParts);
console.log(newPath);

hard

A. '/usr/local/bin/backup/'

B. '/usr/local/bin/node/backup'

C. '/usr/local/bin/node'

D. '/usr/local/bin/backup/node'

Solution

1. Step 1: Analyze how updatedParts modifies dir

   updatedParts copies all parts but changes dir to parts.dir + '/backup', so dir becomes '/usr/local/bin/backup'.

2. Step 2: Understand path.format output

   path.format builds path from updatedParts, combining dir and base ('node'), resulting in '/usr/local/bin/backup/node'.

3. Final Answer:

   '/usr/local/bin/backup/node' -> Option D

4. Quick Check:

   Modified dir + base = '/usr/local/bin/backup/node' [OK]

Hint: Changing dir in parts changes folder path in output [OK]

Common Mistakes:

• Appending backup to base instead of dir
• Confusing order of path parts
• Forgetting to spread parts before modifying