Amazon CodeCatalyst is no longer open to new customers. Existing customers can continue to use the service as normal. For more information, see [How to migrate from CodeCatalyst](migration.md).

# npm tag handling
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npm registries support *tags*, which are string aliases for package versions. You can use tags to provide an alias instead of using version numbers. For example, you have a project with multiple streams of development and you use a different tag for each stream (for example, `stable`, `beta`, `dev`, `canary`). For more information, see [dist-tag](https://docs.npmjs.com/cli/dist-tag) on *npm Docs*. 

By default, npm uses the `latest` tag to identify the current version of a package. `npm install pkg` (without `@version` or `@tag` specifier) installs the latest tag. Typically, projects only use the latest tag for stable release versions. Other tags are used for unstable or prerelease versions. 

## Editing tags with the npm client
<a name="editing-tags-with-the-npm-client"></a>

 The three `npm dist-tag` commands (`add`, `rm`, and `ls`) function the same way in CodeCatalyst package repositories as they function in the [default npm registry](https://registry.npmjs.com/).

## npm tags and upstream repositories
<a name="packages-tags-and-upstreams"></a>

When `npm` requests the tags for a package and versions of that package are also present in an upstream repository, CodeCatalyst merges the tags before returning them to the client. For example, a repository named `R` has an upstream repository named `U`. The following table shows the tags for a package named `web-helper` that's present in both repositories.


****  

| Repository | Package name | Package tags | 
| --- | --- | --- | 
|  R  |  `web-helper`  |   *latest* (alias for version 1.0.0)  | 
|  U  |  `web-helper`  |   *alpha* (alias for version 1.0.1)  | 

In this case, when the npm client fetches the tags for the `web-helper` package from repository `R`, it receives both the *latest* and *alpha* tags. The versions the tags point to won't change.

When the same tag is present on the same package in both the upstream and local repository, CodeCatalyst uses the tag that was *last updated*. For example, suppose that the tags on *webhelper* have been modified to look like the following.


****  

| Repository | Package name | Package tags | Last updated | 
| --- | --- | --- | --- | 
|  R  |  `web-helper`  |   *latest* (alias for version 1.0.0)  |  January 1, 2023  | 
|  U  |  `web-helper`  |   *latest* (alias for version 1.0.1)  |  June 1, 2023  | 

In this case, when the npm client fetches the tags for package *web-helper* from repository `R`, the *latest* tag will alias the version *1.0.1* because it was updated last. This makes it easy to consume new package versions in an upstream repository that are not yet present in a local repository by running `npm update`.