Master Node.js Path Module: Get, Join, Resolve, and Parse File Paths

Module Overview

In Node.js, the path module is frequently used but can be confusing due to unclear documentation and platform differences; grouping its interfaces by purpose makes it easier to understand.

1 Get Path / Filename / Extension

Get directory: path.dirname(filepath) Get filename: path.basename(filepath) Get extension:

path.extname(filepath)

1.1 Get directory

Example:

var path = require('path');
var filepath = '/tmp/demo/js/test.js';
console.log(path.dirname(filepath)); // /tmp/demo/js

1.2 Get filename

path.basename(filepath)

returns the last part of the path; it does not verify that the name corresponds to an actual file.

var path = require('path');
console.log(path.basename('/tmp/demo/js/test.js')); // test.js
console.log(path.basename('/tmp/demo/js/test')); // test

To obtain the filename without its extension, pass the extension as a second argument:

console.log(path.basename('/tmp/demo/js/test.js', '.js')); // test

1.3 Get extension

Example:

var path = require('path');
var filepath = '/tmp/demo/js/test.js';
console.log(path.extname(filepath)); // .js

Rules: extract from the last '.' to the end; if no '.' exists or the first character is '.', return an empty string.

Extract from the last '.' to the end.

If no '.' or the first character is '.', return an empty string.

Official examples:

path.extname('index.html') // '.html'
path.extname('index.coffee.md') // '.md'
path.extname('index.') // '.'
path.extname('index') // ''
path.extname('.index') // ''

2 Path Combination

path.join([...paths])

path.resolve([...paths])

2.1 path.join

Joins the given paths and normalizes the result.

2.2 path.resolve

Resolves a sequence of paths to an absolute path, similar to executing cd commands in a shell.

Example:

var path = require('path');
// Assuming current working directory is /Users/a/.../node-path
console.log(path.resolve('')); // current working directory
console.log(path.resolve('.')); // current working directory
console.log(path.resolve('/foo/bar', './baz')); // /foo/bar/baz
console.log(path.resolve('/foo/bar', './baz/')); // /foo/bar/baz
console.log(path.resolve('/foo/bar', '/tmp/file/')); // /tmp/file
console.log(path.resolve('www', 'js/upload', '../mod.js')); // /Users/a/.../node-path/www/js/mod.js

3 Path Parsing

Interface:

path.parse(path)

3.1 path.normalize(filepath)

Normalizes a path by resolving '.' and '..', collapsing duplicate separators, and handling trailing slashes.

If the path is empty, returns '.' (the current directory).

Collapses repeated separators (e.g., '//' becomes '/').

Processes '.' and '..' similarly to shell navigation.

Preserves a trailing '/' if present.

In other words, path.normalize is "What is the shortest path I can take that will take me to the same place as the input".

Example demonstrating various cases:

var path = require('path');
var filepath = '/tmp/demo/js/test.js';
var index = 0;
function compare(desc, callback){
  console.log('[Case %d]: %s', ++index, desc);
  callback();
  console.log('
');
}
compare('Empty path', function(){ console.log(path.normalize('')); });
compare('Trailing slash', function(){ console.log(path.normalize('/tmp/demo/js/upload')); console.log(path.normalize('/tmp/demo/js/upload/')); });
compare('Duplicate separators', function(){ console.log(path.normalize('/tmp/demo//js')); });
compare('Path with ..', function(){ console.log(path.normalize('/tmp/demo/js/upload/..')); });
compare('Relative path', function(){ console.log(path.normalize('./demo/js/upload/')); console.log(path.normalize('demo/js/upload/')); });
compare('Edge cases', function(){ console.log(path.normalize('./..')); console.log(path.normalize('..')); console.log(path.normalize('../')); console.log(path.normalize('/../')); console.log(path.normalize('/..')); });

4 File Path Formatting / Parsing

path.format(pathObject)

combines root, dir, base, name, and ext into a path string. path.parse(filepath) performs the inverse operation.

Linux and Windows attribute tables (illustrated with images).

4.1 path.format

root

and dir are interchangeable; root does not automatically add a separator, while dir does. Likewise, base can be replaced by name+ext.

4.2 path.parse

Official example shown in the image below.

5 Get Relative Path

Interface: path.relative(from, to) Returns the relative path from from to to.

If from and to refer to the same location, returns an empty string.

If either argument is empty, returns the current working directory.

Example:

var path = require('path');
var p1 = path.relative('/data/orandea/test/aaa', '/data/orandea/impl/bbb');
console.log(p1); // '../../impl/bbb'
var p2 = path.relative('/data/demo', '/data/demo');
console.log(p2); // ''
var p3 = path.relative('/data/demo', '');
console.log(p3); // '../../Users/a/.../node-path'

6 Platform‑Specific Interfaces / Properties

path.posix

– POSIX (Linux) implementation. path.win32 – Windows implementation. path.sep – Path separator ('/' on Linux, '\' on Windows). path.delimiter – List delimiter (':' on Linux, ';' on Windows).

When using path.win32, you may pass '/' as a separator, but the returned paths will use '\'.

Illustrated examples:

6.1 path.delimiter

Linux example:

Windows example:

7 Related Links

Official documentation: https://nodejs.org/api/path.html#path_path