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# resolve
implements the [node `require.resolve()`
algorithm](https://nodejs.org/api/modules.html#modules_all_together)
such that you can `require.resolve()` on behalf of a file asynchronously and
synchronously
[](http://travis-ci.org/browserify/node-resolve)
# example
asynchronously resolve:
```js
var resolve = require('resolve');
resolve('tap', { basedir: __dirname }, function (err, res) {
if (err) console.error(err);
else console.log(res);
});
```
```
$ node example/async.js
/home/substack/projects/node-resolve/node_modules/tap/lib/main.js
```
synchronously resolve:
```js
var resolve = require('resolve');
var res = resolve.sync('tap', { basedir: __dirname });
console.log(res);
```
```
$ node example/sync.js
/home/substack/projects/node-resolve/node_modules/tap/lib/main.js
```
# methods
```js
var resolve = require('resolve');
```
## resolve(id, opts={}, cb)
Asynchronously resolve the module path string `id` into `cb(err, res [, pkg])`, where `pkg` (if defined) is the data from `package.json`.
options are:
* opts.basedir - directory to begin resolving from
* opts.package - `package.json` data applicable to the module being loaded
* opts.extensions - array of file extensions to search in order
* opts.readFile - how to read files asynchronously
* opts.isFile - function to asynchronously test whether a file exists
* opts.isDirectory - function to asynchronously test whether a directory exists
* `opts.packageFilter(pkg, pkgfile)` - transform the parsed package.json contents before looking at the "main" field
* pkg - package data
* pkgfile - path to package.json
* `opts.pathFilter(pkg, path, relativePath)` - transform a path within a package
* pkg - package data
* path - the path being resolved
* relativePath - the path relative from the package.json location
* returns - a relative path that will be joined from the package.json location
* opts.paths - require.paths array to use if nothing is found on the normal `node_modules` recursive walk (probably don't use this)
For advanced users, `paths` can also be a `opts.paths(request, start, opts)` function
* request - the import specifier being resolved
* start - lookup path
* getNodeModulesDirs - a thunk (no-argument function) that returns the paths using standard `node_modules` resolution
* opts - the resolution options
* opts.moduleDirectory - directory (or directories) in which to recursively look for modules. default: `"node_modules"`
* opts.preserveSymlinks - if true, doesn't resolve `basedir` to real path before resolving.
This is the way Node resolves dependencies when executed with the [--preserve-symlinks](https://nodejs.org/api/all.html#cli_preserve_symlinks) flag.
**Note:** this property is currently `true` by default but it will be changed to
`false` in the next major version because *Node's resolution algorithm does not preserve symlinks by default*.
default `opts` values:
```js
{
paths: [],
basedir: __dirname,
extensions: ['.js'],
readFile: fs.readFile,
isFile: function isFile(file, cb) {
fs.stat(file, function (err, stat) {
if (!err) {
return cb(null, stat.isFile() || stat.isFIFO());
}
if (err.code === 'ENOENT' || err.code === 'ENOTDIR') return cb(null, false);
return cb(err);
});
},
isDirectory: function isDirectory(dir, cb) {
fs.stat(dir, function (err, stat) {
if (!err) {
return cb(null, stat.isDirectory());
}
if (err.code === 'ENOENT' || err.code === 'ENOTDIR') return cb(null, false);
return cb(err);
});
},
moduleDirectory: 'node_modules',
preserveSymlinks: true
}
```
## resolve.sync(id, opts)
Synchronously resolve the module path string `id`, returning the result and
throwing an error when `id` can't be resolved.
options are:
* opts.basedir - directory to begin resolving from
* opts.extensions - array of file extensions to search in order
* opts.readFile - how to read files synchronously
* opts.isFile - function to synchronously test whether a file exists
* opts.isDirectory - function to synchronously test whether a directory exists
* `opts.packageFilter(pkg, dir)` - transform the parsed package.json contents before looking at the "main" field
* pkg - package data
* dir - directory for package.json (Note: the second argument will change to "pkgfile" in v2)
* `opts.pathFilter(pkg, path, relativePath)` - transform a path within a package
* pkg - package data
* path - the path being resolved
* relativePath - the path relative from the package.json location
* returns - a relative path that will be joined from the package.json location
* opts.paths - require.paths array to use if nothing is found on the normal `node_modules` recursive walk (probably don't use this)
* opts.moduleDirectory - directory (or directories) in which to recursively look for modules. default: `"node_modules"`
* opts.preserveSymlinks - if true, doesn't resolve `basedir` to real path before resolving.
This is the way Node resolves dependencies when executed with the [--preserve-symlinks](https://nodejs.org/api/all.html#cli_preserve_symlinks) flag.
**Note:** this property is currently `true` by default but it will be changed to
`false` in the next major version because *Node's resolution algorithm does not preserve symlinks by default*.
default `opts` values:
```js
{
paths: [],
basedir: __dirname,
extensions: ['.js'],
readFileSync: fs.readFileSync,
isFile: function isFile(file) {
try {
var stat = fs.statSync(file);
} catch (e) {
if (e && (e.code === 'ENOENT' || e.code === 'ENOTDIR')) return false;
throw e;
}
return stat.isFile() || stat.isFIFO();
},
isDirectory: function isDirectory(dir) {
try {
var stat = fs.statSync(dir);
} catch (e) {
if (e && (e.code === 'ENOENT' || e.code === 'ENOTDIR')) return false;
throw e;
}
return stat.isDirectory();
},
moduleDirectory: 'node_modules',
preserveSymlinks: true
}
```
## resolve.isCore(pkg)
Return whether a package is in core.
# install
With [npm](https://npmjs.org) do:
```sh
npm install resolve
```
# license
MIT
|
