What is the difference between __dirname and ./ in node.js?

When programming in Node.js and referencing files that are located somewhere in relation to your current directory, is there any reason to use the `__dirname` variable instead of just a regular `./`? I've been using ./ thus far in my code and just discovered the existence of `__dirname`, and essentially want to know whether it would be smart to convert my ./'s to that, and if so, why that would be a smart idea.

`./` refers to the current working directory, except in the `require()` function. When using `require()`, it translates `./` to the directory of the current file called. `__dirname` is always the directory of the current file.

For example, with the following file structure

`/home/user/dir/files/config.json`

{
"hello": "world"
}

`/home/user/dir/files/somefile.txt`

text file

`/home/user/dir/dir.js`

var fs = require('fs');

console.log(require('./files/config.json'));
console.log(fs.readFileSync('./files/somefile.txt', 'utf8'));

If I `cd` into `/home/user/dir` and run `node dir.js` I will get

{ hello: 'world' }
text file

But when I run the same script from `/home/user/` I get

{ hello: 'world' }

Error: ENOENT, no such file or directory './files/somefile.txt'
at Object.openSync (fs.js:228:18)
at Object.readFileSync (fs.js:119:15)
at Object.<anonymous> (/home/user/dir/dir.js:4:16)
at Module._compile (module.js:432:26)
at Object..js (module.js:450:10)
at Module.load (module.js:351:31)
at Function._load (module.js:310:12)
at Array.0 (module.js:470:10)
at EventEmitter._tickCallback (node.js:192:40)

Using `./` worked with `require` but not for `fs.readFileSync`. That's because for `fs.readFileSync`, `./` translates into the cwd (in this case `/home/user/`). And `/home/user/files/somefile.txt` does not exist.

# The gist


In Node.js, `__dirname` is always the directory in which the currently executing script resides ([see this][1]). So if you typed `__dirname` into `/d1/d2/myscript.js`, the value would be `/d1/d2`.

By contrast, `.` gives you the directory from which you ran the `node` command in your terminal window (i.e. your working directory) when you use libraries like `path` and `fs`. Technically, it starts out as your working directory but can be changed using `process.chdir()`.

The exception is when you use `.` with `require()`. The path inside `require` is always relative to the file containing the call to `require`.

# For example...

Let's say your directory structure is

/dir1
/dir2
pathtest.js

and `pathtest.js` contains

var path = require("path");
console.log(". = %s", path.resolve("."));
console.log("__dirname = %s", path.resolve(__dirname));

and you do

cd /dir1/dir2
node pathtest.js

you get

. = /dir1/dir2
__dirname = /dir1/dir2

Your working directory is `/dir1/dir2` so that's what `.` resolves to. Since `pathtest.js` is located in `/dir1/dir2` that's what `__dirname` resolves to as well.

However, if you run the script from `/dir1`

cd /dir1
node dir2/pathtest.js

you get

. = /dir1
__dirname = /dir1/dir2


In that case, your working directory was `/dir1` so that's what `.` resolved to, but `__dirname` still resolves to `/dir1/dir2`.

### Using `.` inside `require`...
If inside `dir2/pathtest.js` you have a `require` call into include a file inside `dir1` you would **always** do

require('../thefile')

because the path inside `require` is always relative to the file in which you are calling it. It has nothing to do with your working directory.

[1]:

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