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				readme.markdown
			
		
		
			
			
		
	
	resolve
implements the node require.resolve()
algorithm
such that you can require.resolve() on behalf of a file asynchronously and
synchronously
example
asynchronously resolve:
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:
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
var resolve = require('resolve');
For both the synchronous and asynchronous methods, errors may have any of the following err.code values:
MODULE_NOT_FOUND: the given path string (id) could not be resolved to a moduleINVALID_BASEDIR: the specifiedopts.basedirdoesn't exist, or is not a directoryINVALID_PACKAGE_MAIN: apackage.jsonwas encountered with an invalidmainproperty (eg. not a string)
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.jsondata applicable to the module being loaded - 
opts.extensions - array of file extensions to search in order
 - 
opts.includeCoreModules - set to
falseto exclude node core modules (e.g.fs) from the search - 
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.realpath - function to asynchronously resolve a potential symlink to its real path
 - 
opts.readPackage(readFile, pkgfile, cb)- function to asynchronously read and parse a package.json file- readFile - the passed 
opts.readFileorfs.readFileif not specified - pkgfile - path to package.json
 - cb - callback
 
 - readFile - the passed 
 - 
opts.packageFilter(pkg, pkgfile, dir)- transform the parsed package.json contents before looking at the "main" field- pkg - package data
 - pkgfile - path to package.json
 - dir - directory for 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_modulesrecursive walk (probably don't use this)For advanced users,
pathscan also be aopts.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_modulesresolution - opts - the resolution options
 
 - 
opts.packageIterator(request, start, opts)- return the list of candidate paths where the packages sources may be found (probably don't use this)- request - the import specifier being resolved
 - start - lookup path
 - getPackageCandidates - a thunk (no-argument function) that returns the paths using standard 
node_modulesresolution - 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
basedirto real path before resolving. This is the way Node resolves dependencies when executed with the --preserve-symlinks flag. Note: this property is currentlytrueby default but it will be changed tofalsein the next major version because Node's resolution algorithm does not preserve symlinks by default. 
default opts values:
{
    paths: [],
    basedir: __dirname,
    extensions: ['.js'],
    includeCoreModules: true,
    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);
        });
    },
    realpath: function realpath(file, cb) {
        var realpath = typeof fs.realpath.native === 'function' ? fs.realpath.native : fs.realpath;
        realpath(file, function (realPathErr, realPath) {
            if (realPathErr && realPathErr.code !== 'ENOENT') cb(realPathErr);
            else cb(null, realPathErr ? file : realPath);
        });
    },
    readPackage: function defaultReadPackage(readFile, pkgfile, cb) {
        readFile(pkgfile, function (readFileErr, body) {
            if (readFileErr) cb(readFileErr);
            else {
                try {
                    var pkg = JSON.parse(body);
                    cb(null, pkg);
                } catch (jsonErr) {
                    cb(null);
                }
            }
        });
    },
    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.includeCoreModules - set to
falseto exclude node core modules (e.g.fs) from the search - 
opts.readFileSync - 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.realpathSync - function to synchronously resolve a potential symlink to its real path
 - 
opts.readPackageSync(readFileSync, pkgfile)- function to synchronously read and parse a package.json file- readFileSync - the passed 
opts.readFileSyncorfs.readFileSyncif not specified - pkgfile - path to package.json
 
 - readFileSync - the passed 
 - 
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_modulesrecursive walk (probably don't use this)For advanced users,
pathscan also be aopts.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_modulesresolution - opts - the resolution options
 
 - 
opts.packageIterator(request, start, opts)- return the list of candidate paths where the packages sources may be found (probably don't use this)- request - the import specifier being resolved
 - start - lookup path
 - getPackageCandidates - a thunk (no-argument function) that returns the paths using standard 
node_modulesresolution - 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
basedirto real path before resolving. This is the way Node resolves dependencies when executed with the --preserve-symlinks flag. Note: this property is currentlytrueby default but it will be changed tofalsein the next major version because Node's resolution algorithm does not preserve symlinks by default. 
default opts values:
{
    paths: [],
    basedir: __dirname,
    extensions: ['.js'],
    includeCoreModules: true,
    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();
    },
    realpathSync: function realpathSync(file) {
        try {
            var realpath = typeof fs.realpathSync.native === 'function' ? fs.realpathSync.native : fs.realpathSync;
            return realpath(file);
        } catch (realPathErr) {
            if (realPathErr.code !== 'ENOENT') {
                throw realPathErr;
            }
        }
        return file;
    },
    readPackageSync: function defaultReadPackageSync(readFileSync, pkgfile) {
        var body = readFileSync(pkgfile);
        try {
            var pkg = JSON.parse(body);
            return pkg;
        } catch (jsonErr) {}
    },
    moduleDirectory: 'node_modules',
    preserveSymlinks: true
}
install
With npm do:
npm install resolve
license
MIT
