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resolve

implements the node require.resolve() algorithm such that you can require.resolve() on behalf of a file asynchronously and synchronously

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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 module
  • INVALID_BASEDIR: the specified opts.basedir doesn't exist, or is not a directory
  • INVALID_PACKAGE_MAIN: a package.json was encountered with an invalid main property (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.json data applicable to the module being loaded

  • opts.extensions - array of file extensions to search in order

  • opts.includeCoreModules - set to false to 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 file exists and is a directory

  • opts.realpath - function to asynchronously resolve a potential symlink to its real path

  • opts.realpath - function to asynchronously resolve a potential symlink to its real path

  • 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 that contains 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.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_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 flag.

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);
        });
    },
    moduleDirectory: 'node_modules',
    preserveSymlinks: false
}

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 false to exclude node core modules (e.g. fs) from the search

  • 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 file exists and is a directory

  • opts.realpathSync - function to synchronously resolve a potential symlink to its real path

  • 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 that contains 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.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_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 flag.

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;
    },
    moduleDirectory: 'node_modules',
    preserveSymlinks: false
}

install

With npm do:

npm install resolve

license

MIT

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