1# read-package-tree 2 3[](https://travis-ci.org/npm/read-package-tree) 4 5Read the contents of node_modules. 6 7## USAGE 8 9```javascript 10var rpt = require ('read-package-tree') 11rpt('/path/to/pkg/root', function (node, kidName) { 12 // optional filter function– if included, each package folder found is passed to 13 // it to see if it should be included in the final tree 14 // node is what we're adding children to 15 // kidName is the directory name of the module we're considering adding 16 // return true -> include, false -> skip 17}, function (er, data) { 18 // er means that something didn't work. 19 // data is a structure like: 20 // { 21 // package: <package.json data, or an empty object> 22 // package.name: defaults to `basename(path)` 23 // children: [ <more things like this> ] 24 // parent: <thing that has this in its children property, or null> 25 // path: <path loaded> 26 // realpath: <the real path on disk> 27 // isLink: <set if this is a Link> 28 // target: <if a Link, then this is the actual Node> 29 // error: <if set, the error we got loading/parsing the package.json> 30 // } 31}) 32 33// or promise-style 34rpt('/path/to/pkg/root').then(data => { ... }) 35``` 36 37That's it. It doesn't figure out if dependencies are met, it doesn't 38mutate package.json data objects (beyond what 39[read-package-json](http://npm.im/read-package-json) already does), it 40doesn't limit its search to include/exclude `devDependencies`, or 41anything else. 42 43Just follows the links in the `node_modules` hierarchy and reads the 44package.json files it finds therein. 45 46## Symbolic Links 47 48When there are symlinks to packages in the `node_modules` hierarchy, a 49`Link` object will be created, with a `target` that is a `Node` 50object. 51 52For the most part, you can treat `Link` objects just the same as 53`Node` objects. But if your tree-walking program needs to treat 54symlinks differently from normal folders, then make sure to check the 55object. 56 57In a given `read-package-tree` run, a specific `path` will always 58correspond to a single object, and a specific `realpath` will always 59correspond to a single `Node` object. This means that you may not be 60able to pass the resulting data object to `JSON.stringify`, because it 61may contain cycles. 62 63## Errors 64 65Errors parsing or finding a package.json in node_modules will result in a 66node with the error property set. We will still find deeper node_modules 67if any exist. *Prior to `5.0.0` these aborted tree reading with an error 68callback.* 69 70Only a few classes of errors are fatal (result in an error callback): 71 72* If the top level location is entirely missing, that will error. 73* if `fs.realpath` returns an error for any path its trying to resolve. 74
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