96. npm install *** -D/-S的区别和作用
When using npm installthe command to install a dependency package, you can use the -Dor --save-devflag to save the dependency as a dependency of the development environment, and use -Sthe or --saveflag to save the dependency as a dependency of the production environment.
1. -DOr --save-dev: development environment dependency
- These dependencies are usually tools, libraries, or aids for project development, building, testing, and debugging.
- They work during development, but are usually not included in the final production environment when the project is deployed or released.
- Example: Installing
webpackas a development environment dependency:
npm install webpack --save-dev
2. -SOr --save: production environment dependent
- These dependencies are the core libraries or functional modules required by the project at runtime.
- They are required for the project to function properly and will be included in the final production environment.
- Example: Installing
axiosas a production dependency:
npm install axios --save
In package.jsonthe file, dependencies will be stored in different fields:
- Development environment dependencies are held in
devDependenciesthe field. - Production dependencies are stored in
dependenciesthe field.
Example package.jsonfile:
{
"name": "my-project",
"version": "1.0.0",
"devDependencies": {
"webpack": "^5.0.0"
},
"dependencies": {
"axios": "^0.21.1"
}
}
In the example above, webpackis stored in devDependenciesthe field and axiosis stored in dependenciesthe field.
By explicitly saving the dependencies in different fields, the dependencies of the development environment and the production environment can be clearly distinguished, which is convenient for management and maintenance.
Using the -Dand -Sflags ensures that your project's dependencies are saved correctly in the appropriate fields, and that you npm installdon't confuse development and production dependencies when using install dependencies. This helps improve maintainability and reliability of the project.