Difference Between npm i and npm ci in Node.js

Dealing with Node.js, using npm (Node Package Manager), is important for creating and installing the necessary packages for the project. While most developers know what happens when running npm install or npm i, the npm ci often appears in discussions about continuous integration and continuous delivery pipelines alongside reproducible build processes. This article is about the distinction between "npm i" and "npm ci", the situations in which one should be used over the other, and how each is employed.

What is npm i (or npm install)?

The "npm i" is actually an abbreviation for npm install, which is the main command used in an application that's aimed at installing the dependencies listed in the package.json file.

Key functions of npm i

1. Installs all dependencies listed in package.json.

2. If a package-lock.json file exists, "npm i" will:

• Inspect it for having identical dependency versions all across.
• This is done by running the command npm install. If there are changes to package.json, like adding a new dependency, then the package-lock.json will be updated.

3. Creates or overwrites the package-lock.json file, which indicates the latest installed versions.

4. If such a folder is not present, then it will create a node_modules folder. If such a folder is present, it copies only the necessary dependencies that were not yet installed.

5. Supports version flexibility: If no package-lock.json is present, it will download versions that in package.json version constraints say to.

When to use npm i?

• Development phase: While including, updating and pruning, dependencies.
• Non-CI environments: When variation in versioning is fine, not merely reproducibility.

What is npm ci?

The npm ci still means "continuous integration". It is built for the permanently unattended environment with idempotent builds required, for instance, in the CI/CD workflows.

Key functions of npm ci

A copy must be made from the working project that has the package-lock.json and node_modules directory. npm ci - if package-lock.json file is not available then it will cause an error.

1. Performs a clean install: It removes the node_modules directory and deploys packages more specifically as they are in the package-lock.json file.

2. Faster than npm i: Compare to npm install, if only package-lock.json is used and the version resolution process is bypassed, npm ci runs much faster which will be good in stewarding CI/CD.

3. Does not update package-lock.json: This also guarantees that the package-lock.json does not change because you do not want the version to be changed when deploying.

When to use npm ci?

• CI/CD pipelines: Reproducible builds because npm ci command installs the exact same dependency version every time.
• Production environments: Ensures that the production environment copies the versions used in the testing environment.
• Quick setup: Because of faster installation, it is applicable where installation is critical and the dependency changes are small.

Key differences between npm i and npm ci

The following table highlights the major differences between "npm i" and "npm ci" -

Example Scenarios

1. Working on a New Feature: To install dependencies and add or modify packages, make use of the "npm i" command. This will also change the package-lock.json to new changes if any.

2. Deploying a Web App in CI/CD: Please use "npm ci" for the exact versions as defined in the package-lock.json file that is going to be installed. This ensures that there are replicas of the environment, which is important for avoiding some deployments' problems.

3. Fresh Clone of a Repository: If you are working with a new clone where you desire to get the precise dependencies installed that are specified in package.json, use npm ci instead of npm i. That way, installation is very fast, and they do not build from source, hence overcoming any potential problem arising from updated dependency versions.

Best Practices for npm i and npm ci

• Keep package-lock.json Updated: Make sure that you check in the package-lock.json file frequently to be sure that you have the correct dependency tree.
• Use npm ci in CI/CD Pipelines: It's used exclusively in CI/CD situations where the accidental use of npm install can cause version mismatches.
• Run npm i Locally: Use "npm ci" Remotely: For local development, "npm i" is more relaxed, whereas in remote build or deployment, "npm ci" brings consistency.

Conclusion

Both npm i and npm ci are very important commands that have specific roles in projects written in Node.js. While npm i is useful and appropriate for development, npm ci is conceived with the purpose of being deterministic and ideal for the production pipeline. In this article, we demonstrated how the difference between development and operation teams should be recognized and how it can be utilized to optimize the dev process and increase the reliability of the deployment.