What is the point of having resolved URL in package-lock.json?

Question

whenever I generate a package-lock file, there is also "resolved" block that looks like this:

"resolved": "http://devel.npm.registry:4873/lodash/-/lodash-4.17.5.tgz" 

What is the point of this URL? Later, if I try to install dependencies based on this package-lock, do I need to use the same npm registry? Because we use a different npm registry for local development and for production builds. Thus when I develop, I use devel.npm.registry, but the CI tool uses production.npm.registry. According to my tests, the URL doesn't matter (I tried [email protected]). But it is current implementation that's gonna change soon or is the URL intentionally ignored? I have the feeling that some of the previous versions of npm actually checked the resolved URLs.

The documentation isn't much helpful in this case.

Answer 1

I found some articles on the web regarding this question. Follow the links:

npm uses a JSON as a format for the lock file. The good news is since [email protected] ignores the resolved field on package-lock.json file and basically fallback to the one defined in the .npmrc or via --registry argument using the CLI in case is exist, otherwise, it will use the defined in the resolved field.

https://medium.com/verdaccio/verdaccio-and-deterministic-lock-files-5339d82d611e

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Another day, another tweet about #npm5 goodies.

npm is now agnostic about which registry you used to generate the package-lock.json.

https://twitter.com/maybekatz/status/862834964932435969

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The purpose of resolved in package-lock.json is to bypass the dependency resolution step (fetching metadata) when you are missing packages. integrity is to verify that you're getting the same thing. Without the resolved field, uncached installations can break due to metadata changes, and they'll also be significantly slower because we have to do a full metadata fetch before we can actually download anything.

Note that package-lock.json does not allow different packages to be fetched from different registries. Even if you have a package lock with different packages using different resolved fields, all of the packages will always be fetched from whatever your current registry= setting is, in npmrc. resolved fields that do not match the configured registry will go through the (slower) metadata fetching I mentioned above, but will still be fetched only from the current registry.

https://github.com/npm/npm/issues/16849#issuecomment-312442508