Conclusion ：

1. npm uninstall It will back up the package itself node_modules,rm -f Will delete the entire directory
2. npm uninstall The dependent packages will not be deleted . Even if you explicitly want to delete this package , But it is dependent and will not be deleted .rm -f Meeting
3. npm uninstall There is a global mode , Also delete the soft chain ,rm -r Delete directory only , The soft chain may be missed
4. npm uninstall Will delete package.json Medium dependencies entry ,rm -r Can't
5. npm uninstall Will install those in package.json Missing package ,rm -r Of course, there can be no such side effect

All in all ,npm uninstall and npm install It's the same set of code , The same logic , All are 【 Synchronize the current package environment 】 The operation of . and rm -r Is to forcibly delete a directory .

In terms of name ,uninstall It's really not well named , It's very complicated , and install As complex as , As a whole npm The core of design , Easily misunderstood as deletion .

No documents , Only look at the code , Ah

analysis ：

such as , To delete mkdirp

npm uninstall mkdir

Will perform the following operations

First step Load the local actual package list

readLocalPackageData （ If you use -g The global mode will execute readGlobalPackageData, This line does not show ）

read-package-tree

This is a bag , This package will read recursively node_modules Bag under , Return to a list of heavy objects .

The second step load package.json Get a list of ideal packages

 Through analysis package.json Get the list 

loadAllDepsIntoIdealTree

 stay IdealTree Filter out the package to be deleted , So you get two Tree, One is  CurrentTree, One is  IdealTree

The third step Sync CurrentTree and IdealTree

1. If CurrentTree in ,IdealTree Does not exist in the , Ignore
2. If CurrentTree Does not exist in the ,IdealTree in , Install
2. If CurrentTree in ,IdealTree Does not exist in the , Delete

Step four The logic of deleting

1. If the package to be deleted is currently IdealTree Other packages in depend on , Do not delete
2. If there are dependent packages in the package to be deleted , Then back them up , Recover later

mv ./node_modules/mkdirp/node_modules ./node_modules/.mkdirp.MODULES
rm -rf ./node_modules/mkdirp/
mkdir ./node_modules/mkdirp
mv ./node_modules/.mkdirp.MODULES ./node_modules/mkdirp/node_modules

 Use  rimraf Delete directory ,rimraf It's a bag , It offers something like rm -rf The function of , Recursively delete directories and files , There is retry logic .

It seems simple rm -rf Why should we implement it alone ？

nodejs fs The module was not provided in the early stage rm -r The function of ,fs The module only provides the ability to delete a single directory and a single file .

stay v12.10.0 After that, it provides the method of recursively deleting directories api, stay v14.14.0 Provides rm -rf Of api.

It's too late , So in development npm When , We used rimraf This package .

If you want to delete the package , No, node_modules, The backup operation will not be performed .

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