Have you ever wondered if there's a quick way to only install npm packages when your package.json file has been modified? Well, you're in the right place! In this article, we'll explore how you can use npm to install packages only if your package.json file has been updated.
First things first, let's understand why you might want to do this. Imagine you're working on a project, and you frequently make changes to your package.json file to add new dependencies or update existing ones. Running `npm install` every time, even when your package.json hasn't changed much, can be time-consuming. This is where the `--only=prod` flag comes in handy.
When you run `npm install --only=prod`, npm will only install packages listed under the "dependencies" key in your package.json file. This means npm will ignore packages listed under the "devDependencies" key, as they are typically used for development purposes. By using this flag, npm can skip unnecessary package installations, saving you time and bandwidth.
But what if you want npm to reinstall all packages, including those under "devDependencies," only when your package.json has been modified? Here's where the `--no-save` flag can be useful. When you run `npm install --no-save`, npm will install all packages listed in your package.json file, regardless of whether it's a production or development dependency.
Combining the `--no-save` flag with the `--only=prod` flag can give you the flexibility to control how npm installs packages based on your specific needs. If you want npm to install only production dependencies and ignore development dependencies, you can use `npm install --only=prod --no-save`.
To automate the process further, you can leverage npm scripts in your package.json file. By adding a custom script that checks if the package.json file has been modified before running `npm install`, you can ensure that npm only installs packages when necessary. Here's an example script you can add to your package.json file:
"scripts": {
"install-if-modified": "git diff --quiet --exit-code package.json || npm install"
}In this script, we use `git diff` to check if the package.json file has been modified. If there are differences, npm install will be triggered. You can then run `npm run install-if-modified` to conveniently install packages only when your package.json file has changed.
In summary, by combining the `--only=prod` and `--no-save` flags with npm scripts, you can optimize the installation of packages based on changes to your package.json file. This approach helps you save time and streamline your development workflow by ensuring that npm installs packages efficiently. So, next time you want to install npm packages selectively depending on your package.json modifications, give these techniques a try!