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6 folders - Folder Structures Used by npm
7 Description
9 npm puts various things on your computer. That's its job.
10 This document will tell you what it puts where.
12 tl;dr
14 • Local install (default): puts stuff in ./node_modules of the cur‐
15 rent package root.
16 • Global install (with -g): puts stuff in /usr/local or wherever node
18 is installed.
19 • Install it locally if you're going to require() it.
21 • Install it globally if you're going to run it on the command line.
23 • If you need both, then install it in both places, or use npm link.
25 prefix Configuration
28 The prefix config ⟨/using-npm/config#prefix⟩ defaults to the location
29 where node is installed. On most systems, this is /usr/local. On Win‐
30 dows, it's %AppData%\npm. On Unix systems, it's one level up, since
31 node is typically installed at {prefix}/bin/node rather than {pre‐
32 fix}/node.exe.
33 When the global flag is set, npm installs things into this prefix. When
35 it is not set, it uses the root of the current package, or the current
36 working directory if not in a package already.
37 Node Modules
39 Packages are dropped into the node_modules folder under the prefix.
40 When installing locally, this means that you can require("packagename")
41 to load its main module, or require("packagename/lib/path/to/sub/mod‐
42 ule") to load other modules.
43 Global installs on Unix systems go to {prefix}/lib/node_modules. Global
45 installs on Windows go to {prefix}/node_modules (that is, no lib
46 folder.)
47 Scoped packages are installed the same way, except they are grouped to‐
49 gether in a sub-folder of the relevant node_modules folder with the
50 name of that scope prefix by the @ symbol, e.g. npm install @my‐
51 org/package would place the package in {prefix}/node_modules/@my‐
52 org/package. See npm help scope for more details.
53 If you wish to require() a package, then install it locally.
55 Executables
57 When in global mode, executables are linked into {prefix}/bin on Unix,
58 or directly into {prefix} on Windows. Ensure that path is in your ter‐
59 minal's PATH environment to run them.
60 When in local mode, executables are linked into ./node_modules/.bin so
62 that they can be made available to scripts run through npm. (For exam‐
63 ple, so that a test runner will be in the path when you run npm test.)
64 Man Pages
66 When in global mode, man pages are linked into {prefix}/share/man.
67 When in local mode, man pages are not installed.
69 Man pages are not installed on Windows systems.
71 Cache
73 See npm help cache. Cache files are stored in ~/.npm on Posix, or %Lo‐
74 calAppData%/npm-cache on Windows.
75 This is controlled by the cache config ⟨/using-npm/config#cache⟩ param.
77 Temp Files
79 Temporary files are stored by default in the folder specified by the
80 tmp config ⟨/using-npm/config#tmp⟩, which defaults to the TMPDIR, TMP,
81 or TEMP environment variables, or /tmp on Unix and c:\windows\temp on
82 Windows.
83 Temp files are given a unique folder under this root for each run of
85 the program, and are deleted upon successful exit.
86 More Information
88 When installing locally, npm first tries to find an appropriate prefix
89 folder. This is so that npm install foo@1.2.3 will install to the sen‐
90 sible root of your package, even if you happen to have cded into some
91 other folder.
92 Starting at the $PWD, npm will walk up the folder tree checking for a
94 folder that contains either a package.json file, or a node_modules
95 folder. If such a thing is found, then that is treated as the effective
96 "current directory" for the purpose of running npm commands. (This be‐
97 havior is inspired by and similar to git's .git-folder seeking logic
98 when running git commands in a working dir.)
99 If no package root is found, then the current folder is used.
101 When you run npm install foo@1.2.3, then the package is loaded into the
103 cache, and then unpacked into ./node_modules/foo. Then, any of foo's
104 dependencies are similarly unpacked into ./node_modules/foo/node_mod‐
105 ules/....
106 Any bin files are symlinked to ./node_modules/.bin/, so that they may
108 be found by npm scripts when necessary.
109 Global Installation
111 If the global config ⟨/using-npm/config#global⟩ is set to true, then
112 npm will install packages "globally".
113 For global installation, packages are installed roughly the same way,
115 but using the folders described above.
116 Cycles, Conflicts, and Folder Parsimony
118 Cycles are handled using the property of node's module system that it
119 walks up the directories looking for node_modules folders. So, at every
120 stage, if a package is already installed in an ancestor node_modules
121 folder, then it is not installed at the current location.
122 Consider the case above, where foo -> bar -> baz. Imagine if, in addi‐
124 tion to that, baz depended on bar, so you'd have: foo -> bar -> baz ->
125 bar -> baz .... However, since the folder structure is: foo/node_mod‐
126 ules/bar/node_modules/baz, there's no need to put another copy of bar
127 into .../baz/node_modules, since when baz calls require("bar"), it will
128 get the copy that is installed in foo/node_modules/bar.
129 This shortcut is only used if the exact same version would be installed
131 in multiple nested node_modules folders. It is still possible to have
132 a/node_modules/b/node_modules/a if the two "a" packages are different
133 versions. However, without repeating the exact same package multiple
134 times, an infinite regress will always be prevented.
135 Another optimization can be made by installing dependencies at the
137 highest level possible, below the localized "target" folder (hoisting).
138 Since version 3, npm hoists dependencies by default.
139 Example
141 Consider this dependency graph:
142 foo
144 +-- blerg@1.2.5
145 +-- bar@1.2.3
146 | +-- blerg@1.x (latest=1.3.7)
147 | +-- baz@2.x
148 | | `-- quux@3.x
149 | | `-- bar@1.2.3 (cycle)
150 | `-- asdf@*
151 `-- baz@1.2.3
152 `-- quux@3.x
153 `-- bar
154 In this case, we might expect a folder structure like this (with all
156 dependencies hoisted to the highest level possible):
157 foo
159 +-- node_modules
160 +-- blerg (1.2.5) <---[A]
161 +-- bar (1.2.3) <---[B]
162 | +-- node_modules
163 | +-- baz (2.0.2) <---[C]
164 +-- asdf (2.3.4)
165 +-- baz (1.2.3) <---[D]
166 +-- quux (3.2.0) <---[E]
167 Since foo depends directly on bar@1.2.3 and baz@1.2.3, those are in‐
169 stalled in foo's node_modules folder.
170 Even though the latest copy of blerg is 1.3.7, foo has a specific de‐
172 pendency on version 1.2.5. So, that gets installed at [A]. Since the
173 parent installation of blerg satisfies bar's dependency on blerg@1.x,
174 it does not install another copy under [B].
175 Bar [B] also has dependencies on baz and asdf. Because it depends on
177 baz@2.x, it cannot re-use the baz@1.2.3 installed in the parent
178 node_modules folder [D], and must install its own copy [C]. In order to
179 minimize duplication, npm hoists dependencies to the top level by de‐
180 fault, so asdf is installed under [A].
181 Underneath bar, the baz -> quux -> bar dependency creates a cycle. How‐
183 ever, because bar is already in quux's ancestry [B], it does not unpack
184 another copy of bar into that folder. Likewise, quux's [E] folder tree
185 is empty, because its dependency on bar is satisfied by the parent
186 folder copy installed at [B].
187 For a graphical breakdown of what is installed where, use npm ls.
189 Publishing
191 Upon publishing, npm will look in the node_modules folder. If any of
192 the items there are not in the bundleDependencies array, then they will
193 not be included in the package tarball.
194 This allows a package maintainer to install all of their dependencies
196 (and dev dependencies) locally, but only re-publish those items that
197 cannot be found elsewhere. See package.json ⟨/configuring-npm/package-
198 json⟩ for more information.
199 See also
201 • package.json ⟨/configuring-npm/package-json⟩
202 • npm help install
204 • npm help pack
206 • npm help cache
208 • npm help config
210 • npm help npmrc
212 • npm help config
214 • npm help publish
216 November 2023 FOLDERS(5)