node/deps/npm/doc/cli/dedupe.md

npm-dedupe(1) -- Reduce duplication

SYNOPSIS

npm dedupe [package names...]

DESCRIPTION

Searches the local package tree and attempts to simplify the overall structure by moving dependencies further up the tree, where they can be more effectively shared by multiple dependent packages.

For example, consider this dependency graph:

a
+-- b <-- depends on c@1.0.x
|   `-- c@1.0.3
`-- d <-- depends on c@~1.0.9
    `-- c@1.0.10

In this case, npm-dedupe(1) will transform the tree to:

a
+-- b
+-- d
`-- c@1.0.10

Because of the hierarchical nature of node's module lookup, b and d will both get their dependency met by the single c package at the root level of the tree.

If a suitable version exists at the target location in the tree already, then it will be left untouched, but the other duplicates will be deleted.

If no suitable version can be found, then a warning is printed, and nothing is done.

If any arguments are supplied, then they are filters, and only the named packages will be touched.

Note that this operation transforms the dependency tree, and may result in packages getting updated versions, perhaps from the npm registry.

This feature is experimental, and may change in future versions.

SEE ALSO

• npm-ls(1)
• npm-update(1)
• npm-install(1)