Deleting `package-lock.json` to Resolve Conflicts quickly

Yes it can have bad side effects, maybe not very often but for example you can have in package.json "moduleX": "^1.0.0" and you used to have "moduleX": "1.0.0" in package-lock.json.

By deleting package-lock.json and running npm install you could be updating to version 1.0.999 of moduleX without knowing about it and maybe they have created a bug or done a backwards breaking change (not following semantic versioning).

Anyway there is already a standard solution for it.

1. Fix the conflict inside package.json
2. Run: npm install --package-lock-only

Check out this link for more info:

https://docs.npmjs.com/cli/v6/configuring-npm/package-locks#resolving-lockfile-conflicts

Yes, it can and will affect all the project in really bad way.

1. if your team does not run npm install after each git pull you all are using different dependencies' versions. So it ends with "but it works for me!!" and "I don't understand why my code does not work for you"

2. even if all the team runs npm install it still does not mean everything is ok. at some moment you may find your project acts differently. in a part that you have not been changing for years. and after (probably, quite painful) debugging you will find it's because of 3rd level dependency has updated for next major version and this led some breaking changes.

Conclusion: don't ever delete package-lock.json.

Yes, for first level dependencies if we specify them without ranges (like "react": "16.12.0") we get the same versions each time we run npm install. But we cannot say the same about dependencies of 2+ level deep (dependencies that our dependencies are relying on), so package-lock.json is really important for stability.

In your case you better do next way:

1. fix conflicts in package.json
2. run npm install

As easy as it looks. The same to yarn - it fixes lockfile conflict on its own. The only requirement here to resolve all the conflicts in package.json beforehand if any.

Per docs npm will fix merge conflicts in package-lock.json for you.

[Upd from 2021] important! If you use some library already and npm/GitHub account of its maintainer is hacked. And new version with malicious code inside is released. And you have package-lock.json intact. You will be fine. If you drop it you are in trouble.