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[DOCS] npm scripts update #729

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[DOCS] npm scripts update #729

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2012f52
First take on breaking out the lifecycle hooks.
seanhealy Oct 29, 2018
e95987c
docs: updated scripts docs in using-npm section
Jan 27, 2020
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167 changes: 87 additions & 80 deletions docs/content/using-npm/scripts.md
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Expand Up @@ -10,90 +10,64 @@ description: How npm handles the "scripts" field

### Description

npm supports the "scripts" property of the package.json file, for the
following scripts:

* **prepublish** (_as of npm@5, `prepublish` is deprecated. Use `prepare` for build steps and `prepublishOnly` for upload-only._):
Run BEFORE the package is packed and published, as well as on local `npm
install` without any arguments. (See below)
* **prepare**:
Run both BEFORE the package is packed and published, on local `npm
install` without any arguments, and when installing git dependencies (See
below). This is run AFTER `prepublish`, but BEFORE `prepublishOnly`.
* **prepublishOnly**:
Run BEFORE the package is prepared and packed, ONLY on `npm publish`. (See
below.)
* **prepack**:
run BEFORE a tarball is packed (on `npm pack`, `npm publish`, and when
installing git dependencies)
* **postpack**:
Run AFTER the tarball has been generated and moved to its final destination.
* **publish**, **postpublish**:
Run AFTER the package is published.
* **preinstall**:
Run BEFORE the package is installed
* **install**, **postinstall**:
Run AFTER the package is installed.
* **preuninstall**, **uninstall**:
Run BEFORE the package is uninstalled.
* **postuninstall**:
Run AFTER the package is uninstalled.
* **preversion**:
Run BEFORE bumping the package version.
* **version**:
Run AFTER bumping the package version, but BEFORE commit.
* **postversion**:
Run AFTER bumping the package version, and AFTER commit.
* **pretest**, **test**, **posttest**:
Run by the `npm test` command.
* **prestop**, **stop**, **poststop**:
Run by the `npm stop` command.
* **prestart**, **start**, **poststart**:
Run by the `npm start` command.
* **prerestart**, **restart**, **postrestart**:
Run by the `npm restart` command. Note: `npm restart` will run the
stop and start scripts if no `restart` script is provided.
* **preshrinkwrap**, **shrinkwrap**, **postshrinkwrap**:
Run by the `npm shrinkwrap` command.

Additionally, arbitrary scripts can be executed by running `npm
run-script <stage>`. *Pre* and *post* commands with matching
names will be run for those as well (e.g. `premyscript`, `myscript`,
`postmyscript`). Scripts from dependencies can be run with
`npm explore <pkg> -- npm run <stage>`.

#### Prepublish and Prepare

#### Deprecation Note

Since `npm@1.1.71`, the npm CLI has run the `prepublish` script for both `npm
publish` and `npm install`, because it's a convenient way to prepare a package
for use (some common use cases are described in the section below). It has
also turned out to be, in practice, [very
confusing](https://github.com/npm/npm/issues/10074). As of `npm@4.0.0`, a new
event has been introduced, `prepare`, that preserves this existing behavior. A
_new_ event, `prepublishOnly` has been added as a transitional strategy to
allow users to avoid the confusing behavior of existing npm versions and only
run on `npm publish` (for instance, running the tests one last time to ensure
they're in good shape).

See <https://github.com/npm/npm/issues/10074> for a much lengthier
justification, with further reading, for this change.

#### Use Cases

If you need to perform operations on your package before it is used, in a way
that is not dependent on the operating system or architecture of the
target system, use a `prepublish` script. This includes
tasks such as:
The `"scripts"` property of of your `package.json` file supports a number of built-in scripts and their preset life cycle events as well as arbitrary scripts. These all can be executed by running `npm run-script <stage>` or `npm run <stage>` for short. *Pre* and *post* commands with matching names will be run for those as well (e.g. `premyscript`, `myscript`, `postmyscript`). Scripts from dependencies can be run with `npm explore <pkg> -- npm run <stage>`.
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it might be worth noting that although "test" can be user-defined/overridden, "install" can't be (and probably others, like "publish" etc)?

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That's a great point, same with pack. I'll add a "caveats" section. Does that sound right?

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Rather than a caveats section I think what I mean is that we have some shorthands for scripts.

npm run test -> npm test
npm run start -> npm start
npm run build -> npm build
npm run restart -> npm restart

I can't think of any others, can you @ljharb ?

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Shorthands that can be overridden for user scripts would also include version, but I can't think of any others.

It'd be great to exhaustively list BOTH sets - ie, one list of "shorthand commands that run user scripts when present" and "shorthand commands that ignore user scripts even if present" (noting that they all invoke pre/post scripts)


### Pre & Post Scripts

To create "pre" or "post" scripts for any scripts defined in the `"scripts"` section of the `package.json`, simply create another script *with a matching name* and add "pre" or "post" to the beginning of them.

```json
{
"scripts": {
"precompress": "{{ executes BEFORE the `compress` script }}",
"compress": "{{ run command to compress files }}",
"postcompress": "{{ executes AFTER `compress` script }}"
}
}
```

### Life Cycle Scripts

There are some special life cycle scripts that happen only in certain situations. These scripts happen in addtion to the "pre" and "post" script.
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Typo in 'addtion'.

* `prepare`, `prepublish`, `prepublishOnly`, `prepack`, `postpack`

**prepare** (since `npm@4.0.0`)
* Runs BEFORE the package is packed
* Runs BEFORE the package is published
* Runs on local `npm install` without any arguments
* Run AFTER `prepublish`, but BEFORE `prepublishOnly`
* NOTE: If a package being installed through git contains a `prepare` script, its `dependencies` and `devDependencies` will be installed, and the prepare script will be run, before the package is packaged and installed.

**prepublish** (DEPRECATED)
* Same as `prepare`

**prepublishOnly**
* Runs BEFORE the package is prepared and packed, ONLY on `npm publish`.

**prepack**
* Runs BEFORE a tarball is packed (on "`npm pack`", "`npm publish`", and when installing a git dependencies).
* NOTE: "`npm run pack`" is NOT the same as "`npm pack`". "`npm run pack`" is an arbitrary user defined script name, where as, "`npm pack`" is a CLI defined command.

**postpack**
* Runs AFTER the tarball has been generated and moved to its final destination.

#### Prepare and Prepublish

**Deprecation Note: prepublish**

Since `npm@1.1.71`, the npm CLI has run the `prepublish` script for both `npm publish` and `npm install`, because it's a convenient way to prepare a package for use (some common use cases are described in the section below). It has also turned out to be, in practice, [very confusing](https://github.com/npm/npm/issues/10074). As of `npm@4.0.0`, a new event has been introduced, `prepare`, that preserves this existing behavior. A _new_ event, `prepublishOnly` has been added as a transitional strategy to allow users to avoid the confusing behavior of existing npm versions and only run on `npm publish` (for instance, running the tests one last time to ensure they're in good shape).

See <https://github.com/npm/npm/issues/10074> for a much lengthier justification, with further reading, for this change.

**Use Cases**

If you need to perform operations on your package before it is used, in a way that is not dependent on the operating system or architecture of the target system, use a `prepublish` script. This includes tasks such as:

* Compiling CoffeeScript source code into JavaScript.
* Creating minified versions of JavaScript source code.
* Fetching remote resources that your package will use.

The advantage of doing these things at `prepublish` time is that they can be done once, in a
single place, thus reducing complexity and variability.
Additionally, this means that:
The advantage of doing these things at `prepublish` time is that they can be done once, in a single place, thus reducing complexity and variability. Additionally, this means that:

* You can depend on `coffee-script` as a `devDependency`, and thus
your users don't need to have it installed.
Expand All @@ -102,8 +76,41 @@ Additionally, this means that:
* You don't need to rely on your users having `curl` or `wget` or
other system tools on the target machines.

### Default Values
### Life Cycle Operation Order

#### [`npm publish`](/cli-commands/npm-publish)

* `prepublishOnly`
* `prepare`
* `prepublish`
* `publish`
* `postpublish`

#### [`npm pack`](/cli-commands/npm-pack)

* `prepack`
* `postpack`

#### [`npm install`](/cli-commands/npm-install)

* `preinstall`
* `install`
* `postinstall`

Also triggers

* `prepublish` (when on local)
* `prepare` (when on local)

#### [`npm start`](/cli-commands/npm-start)

`npm run start` has an `npm start` shorthand.

* `prestart`
* `start`
* `poststart`

### Default Values
npm will default some script values based on package contents.

* `"start": "node server.js"`:
Expand Down