developers - Developer Guide
So, you've decided to use npm to develop (and maybe publish/deploy) your
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 then do man
npm-thing to get the documentation on a particular topic, or npm help
thing to see the same information.
A package is:
- a) a folder containing a program described by a package.json file
- b) a gzipped tarball containing (a)
- c) a url that resolves to (b)
- d) a <name>@<version> that is published on the registry
- e) a <name>@<tag> that points to (d)
- f) a <name> that has a "latest" tag satisfying
- g) a git url 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:
The commit-ish can be any tag, sha, or branch which can be
supplied as an argument to git checkout. The default is whatever the
repository uses as its default branch.
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.
See npm help package.json for details about what goes in
that file. At the very least, you need:
- name: This should be a string that identifies your project. Please do not
use the "engines" field to explicitly state the versions of node
(or whatever else) that your program requires, and it's pretty well
github repository name. So, node-foo and bar-js are bad
names. foo or 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.
- scripts: 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.
See npm help scripts.
- 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
- 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 help
npm init for more info.
Use a .npmignore file to keep stuff out of your package. If there's no
.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
git, npm looks for .npmignore and .gitignore files
in all subdirectories of your package, not only the root directory.
.npmignore files follow the same pattern rules
as .gitignore files:
- Blank lines or lines starting with # are ignored.
- Standard glob patterns work.
- You can end patterns with a forward slash / to specify a
- You can negate a pattern by starting it with an exclamation point
By default, the following paths and files are ignored, so there's
no need to add them to .npmignore explicitly:
Additionally, everything in node_modules is ignored, except
for bundled dependencies. npm automatically handles this for you, so don't
bother adding node_modules to .npmignore.
The following paths and files are never ignored, so adding them to
.npmignore is pointless:
- README (and its variants)
- CHANGELOG (and its variants)
- LICENSE / LICENCE
If, given the structure of your project, you find
.npmignore to be a maintenance headache, you might instead try
populating the files property of package.json, which is an
array of file or directory names that should be included in your package.
Sometimes manually picking which items to allow is easier to manage than
building a block list.
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
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, of course.)
More info at npm help link.
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:
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:
Use npm ls -g to see if it's there.
To test a local install, go into some other folder, and then
npm install ../my-package
to install it locally into the node_modules folder in that other
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 help 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
Send emails, write blogs, blab in IRC.
Tell the world how easy it is to install your program!
- npm help npm
- npm help init
- npm help package.json
- npm help scripts
- npm help publish
- npm help adduser
- npm help registry
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