Why NPM rocks!

NPM is THE Node.js Package Manager. In this presentation I describe how it works behind the scenes, and why it's so awesome.

Transcript

1. Work  sucks   go  surfing! http://npmjs.org/
2. @lmatteis
3. What  is  NPM? NPM is the package manager for the Node JavaScript platform
4. It puts modules in place so that node can find them... ...and manages dependency conflicts intelligently
5. Imagine you have a project that depends on a module called felix-couchdb
6. $ mkdir my-project $ cd my-project $ npm install felix-couchdb Run the npm install command from within your project directory (or any of the parent folders)
7. What’s going on behind the scenes $ npm install felix-couchdb ?
8. Fetches the package information http://search.npmjs.org/api/felix-couchdb { "_attachments": { "felix-couchdb-1.0.0.tgz": { "content_type": "application/octet-stream", "digest": "md5-uox/epuoVsfQnzTNMW7VqQ==", "length": 13383, "revpos": 3, "stub": true }, "felix-couchdb-1.0.1.tgz": { "content_type": "application/octet-stream", "digest": "md5-ZkipY8lB3rh7/ZSUFrtpiw==", "length": 16937, "revpos": 5, "stub": true }, "felix-couchdb-1.0.2.tgz": { "content_type": "application/octet-stream", "digest": "md5-Z3j31LH/WymAnFFygOf/Qg==", "length": 16813, "revpos": 7, "stub": true } }, "_id": "felix-couchdb", ...
9. Registry API http://search.npmjs.org NPM Registry You can search for packages and add your own through a RESTful HTTP JSON API
10. HTTP +   RESTful = CouchDB Registry API
11. NPM creates a ./node_modules directory and puts the felix-couchdb module in it $ ls node_modules $ cd node_modules $ ls felix-couchdb
12. Each module contains a package.json file which describes the modules dependencies... and other things
13. It reads package.json from within the felix-couchdb directory and downloads the dependencies
14. It does the same thing for each of the dependencies down the tree, until there are no more dependencies
15. You end up with a structure where everything is local to your working directory! my-project/ node_modules/ felix-couchdb/ node_modules/ request
16. If your project is at /home/rick/my-project Node will check these directories for modules: IN ORDER /home/rick/my-project/node_modules /home/rick/node_modules /home/node_modules /node_modules
17. Keeps your dependencies structure simple
18. my-project/ node_modules/ felix-couchdb/ node_modules/ request
19. my-project/ felix-couchdb/ request depends on depends on
20. What if two modules have the same dependency?
21. ./node_modules felix-couchdb /node-xml (v1) ./node_modules /node-xml (v2) My Project jsdom
22. ./node_modules felix-couchdb /node-xml (v1) ./node_modules /node-xml (v2) My Project jsdom
23. ./node_modules felix-couchdb /node-xml (v1) ./node_modules /node-xml (v2) My Project jsdom They both depend on the same module, only different version of it
24. There’s a copy of the module in each project that needs it!
25. This allows programs to localize their dependencies, so that they do not clash
26. LOCALIZATION ZERO  CONFLICTS allows for
27. Great! Now you know what happens when you download an NPM module
28. What’s   next?
29. Use NPM for your own projects