npm - How to actually use package-lock.json for installing based on locked versions?

You need to use the npm ci command to install from package-lock.json.

See: https://blog.npmjs.org/post/171556855892/introducing-npm-ci-for-faster-more-reliable

Update: As Dave pointed out, the command for this situation is now npm ci. It will install from package-lock.json and will not update it. See the documentation for more information.

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According to this comment by a member of the npm CLI team, what you are describing is a "high priority bug".

1. If you have a package.json and you run npm i we generate a package-lock.json from it.

2. If you run npm i against that package.json and package-lock.json, the latter will never be updated, even if the package.json would be happy with newer versions.

3. If you manually edit your package.json to have different ranges and run npm i and those ranges aren't compatible with your package-lock.json then the latter will be updated with version that are compatible with your package.json. Further runs of npm i will be as with 2 above.

If you do run into a case where npm@^5.4.2 mutates a package-lock.json that was otherwise compatible with the paired package.json please open a new issue. This sort of thing would constitute a high priority bug.