enhanced-resolve
Offers an async require.resolve function. It’s highly configurable.
Features
- plugin system
- provide a custom filesystem
- sync and async node.js filesystems included
Getting Started
Install
# npm
npm install enhanced-resolve
# or Yarn
yarn add enhanced-resolveCreating 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 {
NodeJsInputFileSystem,
CachedInputFileSystem,
ResolverFactory
} = 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 | | restrictions | [] | A list of resolve restrictions
| | fileSystem | | The file system which should be used | | resolver |
undefined | A prepared Resolver to which the plugins are attached |
Plugins
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;
this.target = target;
}
apply(resolver) {
const target = resolver.ensureHook(this.target);
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.
Tests
npm testPassing 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()]
...
},
License
Copyright (c) 2012-2016 Tobias Koppers
