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    4.1.0 • Public • Published


    Offers an async require.resolve function. It's highly configurable.


    • plugin system
    • provide a custom filesystem
    • sync and async node.js filesystems included

    Getting Started


    # npm
    npm install enhanced-resolve
    # or Yarn
    yarn add enhanced-resolve

    Creating a Resolver

    The easiest way to create a resolver is to use the createResolver function on ResolveFactory, along with one of the supplied File System implementations.

    const {
    } = require('enhanced-resolve');
    // create a resolver
    const myResolver = ResolverFactory.createResolver({
      // Typical usage will consume the `NodeJsInputFileSystem` + `CachedInputFileSystem`, which wraps the Node.js `fs` wrapper to add resilience + caching.
      fileSystem: new CachedInputFileSystem(new NodeJsInputFileSystem(), 4000),
      extensions: ['.js', '.json']
      /* any other resolver options here. Options/defaults can be seen below */
    // resolve a file with the new resolver
    const context = {};
    const resolveContext = {};
    const lookupStartPath = '/Users/webpack/some/root/dir';
    const request = './path/to-look-up.js';
    myResolver.resolve({}, lookupStartPath, request, resolveContext, (err/*Error*/, filepath/*string*/) => {
      // Do something with the path

    For more examples creating different types resolvers (sync/async, context, etc) see lib/node.js.

    Resolver Options

    Field Default Description
    alias [] A list of module alias configurations or an object which maps key to value
    aliasFields [] A list of alias fields in description files
    cacheWithContext true If unsafe cache is enabled, includes request.context in the cache key
    descriptionFiles ["package.json"] A list of description files to read from
    enforceExtension false Enforce that a extension from extensions must be used
    enforceModuleExtension false Enforce that a extension from moduleExtensions must be used
    extensions [".js", ".json", ".node"] A list of extensions which should be tried for files
    mainFields ["main"] A list of main fields in description files
    mainFiles ["index"] A list of main files in directories
    modules ["node_modules"] A list of directories to resolve modules from, can be absolute path or folder name
    unsafeCache false Use this cache object to unsafely cache the successful requests
    plugins [] A list of additional resolve plugins which should be applied
    symlinks true Whether to resolve symlinks to their symlinked location
    cachePredicate function() { return true }; A function which decides whether a request should be cached or not. An object is passed to the function with path and request properties.
    moduleExtensions [] A list of module extensions which should be tried for modules
    resolveToContext false Resolve to a context instead of a file
    fileSystem The file system which should be used
    resolver undefined A prepared Resolver to which the plugins are attached


    Similar to webpack, the core of enhanced-resolve functionality is implemented as individual plugins that are executed using Tapable. These plugins can extend the functionality of the library, adding other ways for files/contexts to be resolved.

    A plugin should be a class (or its ES5 equivalent) with an apply method. The apply method will receive a resolver instance, that can be used to hook in to the event system.

    Plugin Boilerplate

    class MyResolverPlugin {
      constructor(source, target) {
        this.source = source; = target;
      apply(resolver) {
        const target = resolver.ensureHook(;
        resolver.getHook(this.source).tapAsync("MyResolverPlugin", (request, resolveContext, callback) => {
          // Any logic you need to create a new `request` can go here
          resolver.doResolve(target, request, null, resolveContext, callback);

    Plugins are executed in a pipeline, and register which event they should be executed before/after. In the example above, source is the name of the event that starts the pipeline, and target is what event this plugin should fire, which is what continues the execution of the pipeline. For an example of how these different plugin events create a chain, see lib/ResolverFactory.js, in the //// pipeline //// section.


    npm test

    Build Status

    Passing options from webpack

    If you are using webpack, and you want to pass custom options to enhanced-resolve, the options are passed from the resolve key of your webpack configuration e.g.:

    resolve: {
      extensions: ['', '.js', '.jsx'],
      modules: ['src', 'node_modules'],
      plugins: [new DirectoryNamedWebpackPlugin()]


    Copyright (c) 2012-2016 Tobias Koppers

    MIT (




    npm i enhanced-resolve@4.1.0





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