[node.js] path.join vs path.resolve with __dirname

Is there a difference when using both path.join and path.resolve with __dirname for resolving absolute path in Node.js?

Should one of them be preferred when being used like that (absolute path resolutions are 90% of use cases)?

I.e.

const absolutePath = path.join(__dirname, some, dir);

vs.

const absolutePath = path.resolve(__dirname, some, dir);

Both methods normalize path.

From the doc for path.resolve:

The resulting path is normalized and trailing slashes are removed unless the path is resolved to the root directory.

But path.join keeps trailing slashes

So

__dirname = '/';
path.resolve(__dirname, 'foo/'); // '/foo'
path.join(__dirname, 'foo/'); // '/foo/'

const absolutePath = path.join(__dirname, some, dir);

vs.

const absolutePath = path.resolve(__dirname, some, dir);

path.join will concatenate __dirname which is the directory name of the current file concatenated with values of some and dir with platform-specific separator.

Whereas

path.resolve will process __dirname, some and dir i.e. from right to left prepending it by processing it.

If any of the values of some or dir corresponds to a root path then the previous path will be omitted and process rest by considering it as root

In order to better understand the concept let me explain both a little bit more detail as follows:-

The path.join and path.resolve are two different methods or functions of the path module provided by nodejs.

Where both accept a list of paths but the difference comes in the result i.e. how they process these paths.

path.join concatenates all given path segments together using the platform-specific separator as a delimiter, then normalizes the resulting path. While the path.resolve() process the sequence of paths from right to left, with each subsequent path prepended until an absolute path is constructed.

When no arguments supplied

The following example will help you to clearly understand both concepts:-

My filename is index.js and the current working directory is E:\MyFolder\Pjtz\node

const path = require('path');

console.log("path.join() : ", path.join());
// outputs .
console.log("path.resolve() : ", path.resolve());
// outputs current directory or equivalent to __dirname

Result

? node index.js
path.join() :  .
path.resolve() :  E:\MyFolder\Pjtz\node

path.resolve() method will output the absolute path whereas the path.join() returns . representing the current working directory if nothing is provided

When some root path is passed as arguments

const path=require('path');

console.log("path.join() : " ,path.join('abc','/bcd'));
console.log("path.resolve() : ",path.resolve('abc','/bcd'));

Result i

? node index.js
path.join() :  abc\bcd
path.resolve() :  E:\bcd

path.join() only concatenates the input list with platform-specific separator while the path.resolve() process the sequence of paths from right to left, with each subsequent path prepended until an absolute path is constructed.