Comprehensive Guide to npm Install in Node.js

Node.js Command: npm install

The npm install command is a fundamental operation in Node.js, primarily used for installing dependencies listed in a project's package.json file. It simplifies the process of managing packages and ensures that a project has all the necessary modules for functioning.

Syntax:

npm install [package_name] [options]

• Without Arguments: Installs all dependencies listed in package.json.
• With Arguments: Installs a specific package, optionally specifying the version or scope.
• Options: Additional flags like --save, --save-dev, --global, etc., can be used to customize behavior.

Examples and Code

1. Installing All Dependencies

Code:

# Navigate to your project directory
cd my-project

# Install all dependencies from package.json
npm install

Explanation:

• cd my-project: Navigate to the project folder.
• npm install: Reads package.json and installs all dependencies into the node_modules folder.

2. Installing a Specific Package

Code:

# Install a specific package
npm install express

Explanation:

• express: Name of the package to be installed.
• The command fetches the latest version of express from the npm registry and adds it to the node_modules folder.

3. Saving a Dependency to package.json

Code:

# Save the package as a runtime dependency
npm install lodash --save

Explanation:

• lodash: Name of the package.
• --save: Adds the package to the dependencies section in package.json. (Note: From npm v5 onwards, --save is the default behavior.)

4. Installing a Dev Dependency

Code:

# Save the package as a development dependency
npm install jest --save-dev

Explanation:

• jest: Name of the package.
• --save-dev: Adds the package to the devDependencies section in package.json.

5. Installing Globally

Code:

# Install a package globally
npm install -g nodemon

Explanation:

• -g or --global: Installs the package globally, making it available system-wide.

6. Installing Specific Versions

Code:

# Install a specific version of a package
npm install [email protected]

Explanation:

• @16.13.1: Specifies the version of the package to install.

Additional Information

• node_modules Folder: This is where all installed dependencies are stored locally for a project.
• package-lock.json: Ensures consistent installations by recording the exact versions of dependencies and sub-dependencies.
• Best Practices:
• Always check for outdated packages using npm outdated.
• Use npm ci for automated builds to ensure a clean and consistent dependency setup.

Practical Guides to Node.js Snippets and Examples.