1NPM-SCRIPTS(7) NPM-SCRIPTS(7)
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6 npm-scripts - How npm handles the "scripts" field
7
9 npm supports the "scripts" property of the package.json file, for the
10 following scripts:
11 · prepublish: Run BEFORE the package is packed and published, as well
13 as on local npm install without any arguments. (See below)
14 · prepare: Run both BEFORE the package is packed and published, on
16 local npm install without any arguments, and when installing git
17 dependencies (See below). This is run AFTER prepublish, but BEFORE
18 prepublishOnly.
19 · prepublishOnly: Run BEFORE the package is prepared and packed, ONLY
21 on npm publish. (See below.)
22 · prepack: run BEFORE a tarball is packed (on npm pack, npm publish,
24 and when installing git dependencies)
25 · postpack: Run AFTER the tarball has been generated and moved to its
27 final destination.
28 · publish, postpublish: Run AFTER the package is published.
30 · preinstall: Run BEFORE the package is installed
32 · install, postinstall: Run AFTER the package is installed.
34 · preuninstall, uninstall: Run BEFORE the package is uninstalled.
36 · postuninstall: Run AFTER the package is uninstalled.
38 · preversion: Run BEFORE bumping the package version.
40 · version: Run AFTER bumping the package version, but BEFORE commit.
42 · postversion: Run AFTER bumping the package version, and AFTER commit.
44 · pretest, test, posttest: Run by the npm test command.
46 · prestop, stop, poststop: Run by the npm stop command.
48 · prestart, start, poststart: Run by the npm start command.
50 · prerestart, restart, postrestart: Run by the npm restart command.
52 Note: npm restart will run the stop and start scripts if no restart
53 script is provided.
54 · preshrinkwrap, shrinkwrap, postshrinkwrap: Run by the npm shrinkwrap
56 command.
57 Additionally, arbitrary scripts can be executed by running npm
60 run-script <stage>. Pre and post commands with matching names will be
61 run for those as well (e.g. premyscript, myscript, postmyscript).
62 Scripts from dependencies can be run with npm explore <pkg> -- npm run
63 <stage>.
64
66 DEPRECATION NOTE
67 Since , the npm CLI has run theprepublishscript for bothnpm publishand‐
68 npm install, because it's a convenient way to prepare a package for use
69 (some common use cases are described in the section below). It has
70 also turned out to be, in practice, [very confus‐
71 ing](https://github.com/npm/npm/issues/10074). As of, a new event has
72 been introduced,prepare, that preserves this existing behavior. A _new_
73 event,prepublishOnlyhas been added as a transitional strategy to allow
74 users to avoid the confusing behavior of existing npm versions and only
75 run onnpm publish` (for instance, running the tests one last time to
76 ensure they're in good shape).
77 See https://github.com/npm/npm/issues/10074 for a much lengthier justi‐
79 fication, with further reading, for this change.
80 USE CASES
82 If you need to perform operations on your package before it is used, in
83 a way that is not dependent on the operating system or architecture of
84 the target system, use a prepublish script. This includes tasks such
85 as:
86 · Compiling CoffeeScript source code into JavaScript.
88 · Creating minified versions of JavaScript source code.
90 · Fetching remote resources that your package will use.
92 The advantage of doing these things at prepublish time is that they can
95 be done once, in a single place, thus reducing complexity and variabil‐
96 ity. Additionally, this means that:
97 · You can depend on coffee-script as a devDependency, and thus your
99 users don't need to have it installed.
100 · You don't need to include minifiers in your package, reducing the
102 size for your users.
103 · You don't need to rely on your users having curl or wget or other
105 system tools on the target machines.
106
109 npm will default some script values based on package contents.
110 · "start": "node server.js": If there is a server.js file in the root
112 of your package, then npm will default the start command to node
113 server.js.
114 · "install": "node-gyp rebuild": If there is a binding.gyp file in the
116 root of your package and you haven't defined your own install or pre‐
117 install scripts, npm will default the install command to compile
118 using node-gyp.
119
122 If npm was invoked with root privileges, then it will change the uid to
123 the user account or uid specified by the user config, which defaults to
124 nobody. Set the unsafe-perm flag to run scripts with root privileges.
125
127 Package scripts run in an environment where many pieces of information
128 are made available regarding the setup of npm and the current state of
129 the process.
130 path
132 If you depend on modules that define executable scripts, like test
133 suites, then those executables will be added to the PATH for executing
134 the scripts. So, if your package.json has this:
135 { "name" : "foo"
137 , "dependencies" : { "bar" : "0.1.x" }
138 , "scripts": { "start" : "bar ./test" } }
139 then you could run npm start to execute the bar script, which is
141 exported into the node_modules/.bin directory on npm install.
142 package.json vars
144 The package.json fields are tacked onto the npm_package_ prefix. So,
145 for instance, if you had {"name":"foo", "version":"1.2.5"} in your
146 package.json file, then your package scripts would have the npm_pack‐
147 age_name environment variable set to "foo", and the npm_package_version
148 set to "1.2.5". You can access these variables in your code with
149 process.env.npm_package_name and process.env.npm_package_version, and
150 so on for other fields.
151 configuration
153 Configuration parameters are put in the environment with the npm_con‐
154 fig_ prefix. For instance, you can view the effective root config by
155 checking the npm_config_root environment variable.
156 Special: package.json config object
158 The package.json "config" keys are overwritten in the environment if
159 there is a config param of <name>[@<version>]:<key>. For example, if
160 the package.json has this:
161 { "name" : "foo"
163 , "config" : { "port" : "8080" }
164 , "scripts" : { "start" : "node server.js" } }
165 and the server.js is this:
167 http.createServer(...).listen(process.env.npm_package_config_port)
169 then the user could change the behavior by doing:
171 npm config set foo:port 80
173 current lifecycle event
175 Lastly, the npm_lifecycle_event environment variable is set to which‐
176 ever stage of the cycle is being executed. So, you could have a single
177 script used for different parts of the process which switches based on
178 what's currently happening.
179 Objects are flattened following this format, so if you had
181 {"scripts":{"install":"foo.js"}} in your package.json, then you'd see
182 this in the script:
183 process.env.npm_package_scripts_install === "foo.js"
185
187 For example, if your package.json contains this:
188 { "scripts" :
190 { "install" : "scripts/install.js"
191 , "postinstall" : "scripts/install.js"
192 , "uninstall" : "scripts/uninstall.js"
193 }
194 }
195 then scripts/install.js will be called for the install and post-install
197 stages of the lifecycle, and scripts/uninstall.js will be called when
198 the package is uninstalled. Since scripts/install.js is running for
199 two different phases, it would be wise in this case to look at the
200 npm_lifecycle_event environment variable.
201 If you want to run a make command, you can do so. This works just
203 fine:
204 { "scripts" :
206 { "preinstall" : "./configure"
207 , "install" : "make && make install"
208 , "test" : "make test"
209 }
210 }
211
213 Scripts are run by passing the line as a script argument to sh.
214 If the script exits with a code other than 0, then this will abort the
216 process.
217 Note that these script files don't have to be nodejs or even javascript
219 programs. They just have to be some kind of executable file.
220
222 If you want to run a specific script at a specific lifecycle event for
223 ALL packages, then you can use a hook script.
224 Place an executable file at node_modules/.hooks/{eventname}, and it'll
226 get run for all packages when they are going through that point in the
227 package lifecycle for any packages installed in that root.
228 Hook scripts are run exactly the same way as package.json scripts.
230 That is, they are in a separate child process, with the env described
231 above.
232
234 · Don't exit with a non-zero error code unless you really mean it.
235 Except for uninstall scripts, this will cause the npm action to fail,
236 and potentially be rolled back. If the failure is minor or only will
237 prevent some optional features, then it's better to just print a
238 warning and exit successfully.
239 · Try not to use scripts to do what npm can do for you. Read through
241 npm help 5 package.json to see all the things that you can specify
242 and enable by simply describing your package appropriately. In gen‐
243 eral, this will lead to a more robust and consistent state.
244 · Inspect the env to determine where to put things. For instance, if
246 the npm_config_binroot environment variable is set to /home/user/bin,
247 then don't try to install executables into /usr/local/bin. The user
248 probably set it up that way for a reason.
249 · Don't prefix your script commands with "sudo". If root permissions
251 are required for some reason, then it'll fail with that error, and
252 the user will sudo the npm command in question.
253 · Don't use install. Use a .gyp file for compilation, and prepublish
255 for anything else. You should almost never have to explicitly set a
256 preinstall or install script. If you are doing this, please consider
257 if there is another option. The only valid use of install or prein‐
258 stall scripts is for compilation which must be done on the target
259 architecture.
260
263 · npm help run-script
264 · npm help 5 package.json
266 · npm help 7 developers
268 · npm help install
270 April 2019 NPM-SCRIPTS(7)