默认情况下，npm install尝试全局安装

Question

When performing npm install on a folder, the package is installed on c:\\Users\\<user>\\node-modules instead of .\\<project folder>\\node-modules

I've tried to update npm config save=false but this didn't solve the problem

PS C:\Users\danielk\Documents\udemy_nodejs\FirstExpressApp> npm install express
npm WARN danielk No description
npm WARN danielk No repository field.
npm WARN danielk No license field.

+ express@4.17.1
updated 1 package and audited 126 packages in 2.004s
found 0 vulnerabilities

PS C:\Users\danielk\Documents\udemy_nodejs\FirstExpressApp> dir


    Directory: C:\Users\danielk\Documents\udemy_nodejs\FirstExpressApp


Mode                LastWriteTime         Length Name
----                -------------         ------ ----
-a----       21/08/2019   7:54 AM             27 app.js

When doing npm install express in the project folder, I would expect the node-modules subfolder to be created in the project folder and the express module to be installed in the node-modules subfolder. However its created in C:\\Users\\danielk\\node-modules.

Could anyone help on what is wrong and how this can be fixed?

Answer 1

When you do npm install, npm actually installs the package to the "npm project" you are currently in. See the following example:

eric_@Eric-Dev-Laptop MINGW64 ~/Desktop/mixed/stackoverflow
$ npm init
This utility will walk you through creating a package.json file.
It only covers the most common items, and tries to guess sensible defaults.

See `npm help json` for definitive documentation on these fields
and exactly what they do.

Use `npm install <pkg>` afterwards to install a package and
save it as a dependency in the package.json file.

Press ^C at any time to quit.
package name: (stackoverflow)
[...Truncated...]
Is this OK? (yes)

eric_@Eric-Dev-Laptop MINGW64 ~/Desktop/mixed/stackoverflow
$ mkdir child

eric_@Eric-Dev-Laptop MINGW64 ~/Desktop/mixed/stackoverflow
$ cd child/

eric_@Eric-Dev-Laptop MINGW64 ~/Desktop/mixed/stackoverflow/child
$ npm install express
npm notice created a lockfile as package-lock.json. You should commit this file.
npm WARN stackoverflow@1.0.0 No description
npm WARN stackoverflow@1.0.0 No repository field.

+ express@4.17.1
added 50 packages from 37 contributors and audited 126 packages in 3.021s
found 0 vulnerabilities


eric_@Eric-Dev-Laptop MINGW64 ~/Desktop/mixed/stackoverflow/child
$ ls

eric_@Eric-Dev-Laptop MINGW64 ~/Desktop/mixed/stackoverflow/child
$ ls ..
child/  node_modules/  package.json  package-lock.json

eric_@Eric-Dev-Laptop MINGW64 ~/Desktop/mixed/stackoverflow/child
$ ls ../node_modules/
accepts/              escape-html/        mime/            safer-buffer/
array-flatten/        etag/               mime-db/         send/
body-parser/          express/            mime-types/      serve-static/
bytes/                finalhandler/       ms/              setprototypeof/
content-disposition/  forwarded/          negotiator/      statuses/
content-type/         fresh/              on-finished/     toidentifier/
cookie/               http-errors/        parseurl/        type-is/
cookie-signature/     iconv-lite/         path-to-regexp/  unpipe/
debug/                inherits/           proxy-addr/      utils-merge/
depd/                 ipaddr.js/          qs/              vary/
destroy/              media-typer/        range-parser/
ee-first/             merge-descriptors/  raw-body/
encodeurl/            methods/            safe-buffer/

What happens is, I made a stackoverflow folder, initialized an "npm project" there with npm init , and cd into child folder. When I do npm install express inside, the express module will inadvertently get installed to stackoverflow/node_module . This is such that when you are making a program, eg myprogram, and even when you are in some subfolder inside (eg myprogram/lib/ ) and you perform npm install , the module will still be installed to myprogram.

Comparing this to your case, this is probably because your C:\\Users\\danielk\\ is already an npm project, so when you are in C:\\Users\\danielk\\Documents\\udemy_nodejs\\FirstExpressApp , npm thinks you are in the C:\\Users\\danielk\\ project and thus save the express module there.

As for why C:\\Users\\danielk\\ became an npm project, is it either you manually did npm init there before, or you performed your first npm install there, and C:\\Users\\danielk\\node_modules is created, marking it an npm project.

And one more thing, that express is not installed "globally", you do "global" install by npm install express -g (well though for express there is no use to install it globally). Your case is just the package getting "installed in the home directory".