Node Package Manager (npm) is a powerful package manager for JavaScript and Node.js applications. It's a command-line tool that allows developers to easily install, manage, and share third-party libraries and tools with their projects. Here are some key points about npm:
1. Package Management:
npm is used to install, manage, and update packages (libraries and tools) for Node.js applications. These packages can include everything from small utility libraries to full-fledged frameworks.
2. Centralized Registry:
npm maintains a centralized registry of over a million packages, making it one of the largest software registries in the world. Developers can browse this registry to discover and install packages.
3. Installing Packages:
To install a package, you use the npm install command followed by the package name. For example, to install the popular lodash library, you would run:
npm install lodash
4. Package.json File:
Every Node.js project typically includes a package.json file. This file serves as a manifest for the project and contains information about the project, its dependencies, and other configuration details.
5. Dependencies:
npm automatically manages a project's dependencies. When you install a package, npm also installs any additional packages that the installed package depends on.
6. Global vs. Local Packages:
Packages can be installed either locally (in the project directory) or globally (system-wide). Local packages are typically used as dependencies for your project, while global packages are command-line tools that you can use across different projects.
7. Running Scripts:
npm allows you to define and run custom scripts in your package.json file. This can be used for various tasks like starting a server, running tests, or building your application.
8. Versioning and SemVer:
npm uses semantic versioning (SemVer) to manage package versions. This allows developers to specify version ranges and ensure compatibility with their projects.
9. Publishing Packages:
Developers can publish their own packages to the npm registry, making them available for other developers to use. This is especially useful for open-source projects.
10. Managing Versions:
- npm provides commands to update, uninstall, and manage package versions. For example:
```bash
npm update lodash # Updates the lodash package
npm uninstall lodash # Uninstalls the lodash package
```
11. Scoped Packages:
- Scoped packages are packages with a specific scope or namespace. They are typically used by organizations to group related packages together.
12. Private Packages:
- npm supports private packages, allowing organizations to host their own private registry for internal use.
