section: using-npm title: developers description: Developer Guide —
So, you’ve decided to use npm to develop (and maybe publish/deploy) your project.
There are a few things that you need to do above the simple steps that your users will do to install your program.
These are man pages. If you install npm, you should be able to
man npm-thing to get the documentation on a particular
npm help thing to see the same information.
A package is:
<name>@<version>that is published on the registry with (c)
<name>@<tag>that points to (d)
<name>that has a “latest” tag satisfying (e)
giturl that, when cloned, results in (a).
Even if you never publish your package, you can still get a lot of benefits of using npm if you just want to write a node program (a), and perhaps if you also want to be able to easily install it elsewhere after packing it up into a tarball (b).
Git urls can be of the form:
commit-ish can be any tag, sha, or branch which can be supplied as
an argument to
git checkout. The default is
You need to have a
package.json file in the root of your project to do
much of anything with npm. That is basically the whole interface.
package.json for details about what goes in that file. At the very
least, you need:
It does not necessarily need to match your github repository name.
bar-js are bad names.
bar are better.
version: A semver-compatible version.
engines: Specify the versions of node (or whatever else) that your program runs on. The node API changes a lot, and there may be bugs or new functionality that you depend on. Be explicit.
author: Take some credit.
If you have a special compilation or installation script, then you
should put it in the
scripts object. You should definitely have at
least a basic smoke-test command as the “scripts.test” field.
main: If you have a single module that serves as the entry point to your program (like what the “foo” package gives you at require(“foo”)), then you need to specify that in the “main” field.
directories: This is an object mapping names to folders. The best ones to include are “lib” and “doc”, but if you use “man” to specify a folder full of man pages, they’ll get installed just like these ones.
You can use
npm init in the root of your package in order to get you
started with a pretty basic package.json file. See
npm init for
.npmignore file to keep stuff out of your package. If there’s
.npmignore file, but there is a
.gitignore file, then npm will
ignore the stuff matched by the
.gitignore file. If you want to
include something that is excluded by your
.gitignore file, you can
create an empty
.npmignore file to override it. Like
.gitignore files in all subdirectories of your
package, not only the root directory.
.npmignore files follow the same pattern rules
/to specify a directory.
By default, the following paths and files are ignored, so there’s no
need to add them to
Additionally, everything in
node_modules is ignored, except for
bundled dependencies. npm automatically handles this for you, so don’t
The following paths and files are never ignored, so adding them to
.npmignore is pointless:
README(and its variants)
CHANGELOG(and its variants)
If, given the structure of your project, you find
.npmignore to be a
maintenance headache, you might instead try populating the
package.json, which is an array of file or directory names
that should be included in your package. Sometimes a whitelist is easier
to manage than a blacklist.
If you want to double check that your package will include only the files
you intend it to when published, you can run the
npm pack command locally
which will generate a tarball in the working directory, the same way it
does for publishing.
npm link is designed to install a development package and see the
changes in real time without having to keep re-installing it. (You do
need to either re-link or
npm rebuild -g to update compiled packages,
More info at
This is important.
If you can not install it locally, you’ll have problems trying to publish it. Or, worse yet, you’ll be able to publish it, but you’ll be publishing a broken or pointless package. So don’t do that.
In the root of your package, do this:
npm install . -g
That’ll show you that it’s working. If you’d rather just create a symlink package that points to your working directory, then do this:
npm ls -g to see if it’s there.
To test a local install, go into some other folder, and then do:
cd ../some-other-folder npm install ../my-package
to install it locally into the node_modules folder in that other place.
Then go into the node-repl, and try using require(“my-thing”) to bring in your module’s main module.
Create a user with the adduser command. It works like this:
and then follow the prompts.
This is documented better in npm adduser.
This part’s easy. In the root of your folder, do this:
You can give publish a url to a tarball, or a filename of a tarball, or a path to a folder.
Note that pretty much everything in that folder will be exposed
by default. So, if you have secret stuff in there, use a
.npmignore file to list out the globs to ignore, or publish
from a fresh checkout.
Send emails, write blogs, blab in IRC.
Tell the world how easy it is to install your program!