How to make node.js require absolute? (instead of relative)

I like to make a new node_modules folder for shared code, then let node and require do what it does best.

for example:

- node_modules // => these are loaded from your package.json
- app
  - node_modules // => add node-style modules
    - helper.js
  - models
    - user
    - car
- package.json
- .gitignore

For example, if you're in car/index.js you can require('helper') and node will find it!

How node_modules Work

node has a clever algorithm for resolving modules that is unique among rival platforms.

If you require('./foo.js') from /beep/boop/bar.js, node will look for ./foo.js in /beep/boop/foo.js. Paths that start with a ./ or ../ are always local to the file that calls require().

If however you require a non-relative name such as require('xyz') from /beep/boop/foo.js, node searches these paths in order, stopping at the first match and raising an error if nothing is found:

/beep/boop/node_modules/xyz
/beep/node_modules/xyz
/node_modules/xyz

For each xyz directory that exists, node will first look for a xyz/package.json to see if a "main" field exists. The "main" field defines which file should take charge if you require() the directory path.

For example, if /beep/node_modules/xyz is the first match and /beep/node_modules/xyz/package.json has:

{
  "name": "xyz",
  "version": "1.2.3",
  "main": "lib/abc.js"
}

then the exports from /beep/node_modules/xyz/lib/abc.js will be returned by require('xyz').

If there is no package.json or no "main" field, index.js is assumed:

/beep/node_modules/xyz/index.js

And what about:

var myModule = require.main.require('./path/to/module');

It requires the file as if it were required from the main js file, so it works pretty well as long as your main js file is at the root of your project... and that's something I appreciate.

The big picture

It seems "really bad" but give it time. It is, in fact, really good. The explicit require()s give a total transparency and ease of understanding that is like a breath of fresh air during a project life cycle.

Think of it this way: You are reading an example, dipping your toes into Node.js and you've decided it is "really bad IMO." You are second-guessing leaders of the Node.js community, people who have logged more hours writing and maintaining Node.js applications than anyone. What is the chance the author made such a rookie mistake? (And I agree, from my Ruby and Python background, it seems at first like a disaster.)

There is a lot of hype and counter-hype surrounding Node.js. But when the dust settles, we will acknowledge that explicit modules and "local first" packages were a major driver of adoption.

The common case

Of course, node_modules from the current directory, then the parent, then grandparent, great-grandparent, etc. is searched. So packages you have installed already work this way. Usually you can require("express") from anywhere in your project and it works fine.

If you find yourself loading common files from the root of your project (perhaps because they are common utility functions), then that is a big clue that it's time to make a package. Packages are very simple: move your files into node_modules/ and put a package.json there. Voila! Everything in that namespace is accessible from your entire project. Packages are the correct way to get your code into a global namespace.

Other workarounds

I personally don't use these techniques, but they do answer your question, and of course you know your own situation better than I.

You can set $NODE_PATH to your project root. That directory will be searched when you require().

Next, you could compromise and require a common, local file from all your examples. That common file simply re-exports the true file in the grandparent directory.

examples/downloads/app.js (and many others like it)

var express = require('./express')

examples/downloads/express.js

module.exports = require('../../')

Now when you relocate those files, the worst-case is fixing the one shim module.

There's a really interesting section in the Browserify Handbook:

avoiding ../../../../../../..

Not everything in an application properly belongs on the public npm and the overhead of setting up a private npm or git repo is still rather large in many cases. Here are some approaches for avoiding the ../../../../../../../ relative paths problem.

node_modules

People sometimes object to putting application-specific modules into node_modules because it is not obvious how to check in your internal modules without also checking in third-party modules from npm.

The answer is quite simple! If you have a .gitignore file that ignores node_modules:

node_modules

You can just add an exception with ! for each of your internal application modules:

node_modules/*
!node_modules/foo
!node_modules/bar

Please note that you can't unignore a subdirectory, if the parent is already ignored. So instead of ignoring node_modules, you have to ignore every directory inside node_modules with the node_modules/* trick, and then you can add your exceptions.

Now anywhere in your application you will be able to require('foo') or require('bar') without having a very large and fragile relative path.

If you have a lot of modules and want to keep them more separate from the third-party modules installed by npm, you can just put them all under a directory in node_modules such as node_modules/app:

node_modules/app/foo
node_modules/app/bar

Now you will be able to require('app/foo') or require('app/bar') from anywhere in your application.

In your .gitignore, just add an exception for node_modules/app:

node_modules/*
!node_modules/app

If your application had transforms configured in package.json, you'll need to create a separate package.json with its own transform field in your node_modules/foo or node_modules/app/foo component directory because transforms don't apply across module boundaries. This will make your modules more robust against configuration changes in your application and it will be easier to independently reuse the packages outside of your application.

symlink

Another handy trick if you are working on an application where you can make symlinks and don't need to support windows is to symlink a lib/ or app/ folder into node_modules. From the project root, do:

ln -s ../lib node_modules/app

and now from anywhere in your project you'll be able to require files in lib/ by doing require('app/foo.js') to get lib/foo.js.

custom paths

You might see some places talk about using the $NODE_PATH environment variable or opts.paths to add directories for node and browserify to look in to find modules.

Unlike most other platforms, using a shell-style array of path directories with $NODE_PATH is not as favorable in node compared to making effective use of the node_modules directory.

This is because your application is more tightly coupled to a runtime environment configuration so there are more moving parts and your application will only work when your environment is setup correctly.

node and browserify both support but discourage the use of $NODE_PATH.