Question on "require" - Githubissues

yolapop commented 9 years ago

Hi, I'm a beginner, just a couple of questions :)

When you call require('some_module') in node here is what happens:

if a file called some_module.js exists in the current folder node will load that, otherwise:

node looks in the current folder for a node_modules folder with a some_module folder in it

if it doesn't find it, it will go up one folder and repeat step 2

Isn't it needed to add ./ in require to find local modules? i.e. if I have filter.js in my current directory and I want to load it as a module I would require('./filter').

Also, reading this http://www.bennadel.com/blog/2169-where-does-node-js-and-require-look-for-modules.htm

var utils = require( "utils" );

If the given module is not a core module, Node.js will then begin to search for a directory named, "node_modules". It will start in the current directory (relative to the currently-executing Javascript file in Node) and then work its way up the folder hierarchy, checking each level for a node_modules folder.

Node.js will perform a hierarchical directory search for "node_modules" and "utils" in the following ways:

./node_modules/utils.js ./node_modules/utils/index.js ./node_modules/utils/package.json

I'd like some clarification because the explanation above seems different with yours. Thank you.

max-mapper commented 9 years ago

@yolapop Hi, thanks for the great question.

Isn't it needed to add ./ in require to find local modules?

Yes, you are absolutely correct here. Now that you point that out, I think I should probably update that section as it is currently inaccurate.

Node.js will perform a hierarchical directory search for "node_modules" and "utils" in the following ways:

./node_modules/utils.js ./node_modules/utils/index.js ./node_modules/utils/package.json

I don't think this is technically accurate either... the directory search would look like this instead:

node would check for existence of ./node_modules/utils/package.json
if it does not exist, it will try ../node_modules/utils/package.json
if that does not exist, it will try .../node_modules/utils/package.json etc until it reaches /
when it finds some folder called utils with a package.json in it inside of a node_modules it will read the package.json and check and see if a main property is set. for example, you could set your main to be called utils.js. otherwise if main is not specified it will default to looking for index.js
finally, now that it knows the folder of the utils module and the name of the main entry file, it will require the main entry file

hope this helps!

max-mapper commented 9 years ago

@yolapop also I can highly recommend this nodeschool workshop https://github.com/npm/how-to-npm

yolapop commented 9 years ago

Thanks for the answer and recommendation!

On Sun, Mar 22, 2015, 11:41 PM Max Ogden notifications@github.com wrote:

@yolapop https://github.com/yolapop also I can highly recommend this nodeschool workshop https://github.com/npm/how-to-npm

— Reply to this email directly or view it on GitHub https://github.com/maxogden/art-of-node/issues/51#issuecomment-84651470.

max-mapper / art-of-node

Question on "require" #51