npm-dedupe man page
npm-dedupe — Reduce duplication
npm dedupe npm ddp aliases: find-dupes, ddp
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 firstname.lastname@example.org | `-- email@example.com `-- d <-- depends on c@~1.0.9 `-- firstname.lastname@example.org
In this case, npm help npm-dedupe will transform the tree to:
a +-- b +-- d `-- email@example.com
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.
The deduplication algorithm walks the tree, moving each dependency as far up in the tree as possible, even if duplicates are not found. This will result in both a flat and deduplicated 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.
Arguments are ignored. Dedupe always acts on the entire tree.
Note that this operation transforms the dependency tree, but will never result in new modules being installed.
npm help ls
npm help update
npm help install