what is use of require('.') in node.js

Question

I was reading a node.js cli module documentation and it has one line like this. I know that we can include external modules like this but dont know what is the use of '.' while requiring a module;

const foo = require('.');

Can anyone tell me what is use of it or why its used that way.

Answer 1

It will import index file in the folder where you are running your file will empty require statement. Javascript require module will try to find index.js file if you do not specify any file name(only provide folder reference) in the require() argument.

Basically it's an alias for const foo = require('./index.js');

index.js

module.exports = 1;

foo.js

const foo = require('.');
console.log({ foo });

If both files are in the same folder then it will print

{ foo: 1 }

Answer 2

In require('.'), '.' represent the current directory, and ".." means parent directory.

-- parent 
  -- child1
    -- grandchild1
    -- grandchild2
  -- child2

Now, suppose you are at child1 and want to import files from grandchild1 or inside the subfolder, Then you have to start from the current location (".") to the grandchild location.

require('./grandchild1/filename')

and, if need to import from the parent or outside your current directory, then you have to start backward that is from parent location (".."):

require('../parent/filename') 
// here '..' take you one folder back (parent folder) and if you want to go one more folder back (parent of parent folder) then add one more pair of dots : '../../some_folder'