These options determine how thedifferent types of modules within a project will be treated.

module.defaultRules

An array of rules applied by default for modules.

Seesource code for details.

module.exports={  module:{    defaultRules:['...',// you can use "..." to reference those rules applied by webpack by default],},};

Starting with webpack 5.87.0, falsy values including0,"",false,null andundefined are allowed to pass tomodule.defaultRules to conditionally disable specific rules.

module.exports={  module:{    defaultRules:[false&&{// this rule will be disabled},],},};

module.generator

It's possible to configure all generators' options in one place with amodule.generator.

webpack.config.js

module.exports={  module:{    generator:{      asset:{// Generator options for asset modules// Indicates if this asset should be treated as binary. Set to 'false' to handle it as text instead. Available since webpack 5.93.0        binary:false,// The options for data url generator.        dataUrl:{// Asset encoding (defaults to "base64")// type: 'base64' | false          encoding:'base64',// Asset mimetype (getting from file extension by default).// type: string          mimetype:'image/png',},// Emit an output asset from this asset module. This can be set to 'false' to omit emitting e. g. for SSR.// type: boolean        emit:true,// Customize filename for this asset module// type: string | ((pathData: PathData, assetInfo?: AssetInfo) => string)        filename:'static/[path][name][ext]',// Customize publicPath for asset modules, available since webpack 5.28.0// type: string | ((pathData: PathData, assetInfo?: AssetInfo) => string)        publicPath:'https://cdn/assets/',// Emit the asset in the specified folder relative to 'output.path', available since webpack 5.67.0// type: string | ((pathData: PathData, assetInfo?: AssetInfo) => string)        outputPath:'cdn-assets/',},'asset/inline':{// Generator options for asset/inline modules// Indicates if this asset should be treated as binary. Set to 'false' to handle it as text instead. Available since webpack 5.93.0        binary:false,// The options for data url generator.        dataUrl:{// Asset encoding (defaults to "base64")// type: 'base64' | false          encoding:'base64',// Asset mimetype (getting from file extension by default).// type: string          mimetype:'image/png',},},'asset/resource':{// Generator options for asset/resource modules// Indicates if this asset should be treated as binary. Set to 'false' to handle it as text instead. Available since webpack 5.93.0        binary:false,// Emit an output asset from this asset module. This can be set to 'false' to omit emitting e. g. for SSR.// type: boolean        emit:true,// Customize filename for this asset module// type: string | ((pathData: PathData, assetInfo?: AssetInfo) => string)        filename:'static/[path][name][ext]',// Customize publicPath for asset/resource modules, available since webpack 5.28.0// type: string | ((pathData: PathData, assetInfo?: AssetInfo) => string)        publicPath:'https://cdn/assets/',// Emit the asset in the specified folder relative to 'output.path', available since webpack 5.67.0// type: string | ((pathData: PathData, assetInfo?: AssetInfo) => string)        outputPath:'cdn-assets/',},'asset/bytes':{// No generator options are supported for this module type yet}      javascript:{// No generator options are supported for this module type yet},'javascript/auto':{// ditto},'javascript/dynamic':{// ditto},'javascript/esm':{// ditto},      css:{// Generator options for css modules// Avoid generating and loading a stylesheet and only embed exports from css into output javascript files.// type: boolean, available since webpack 5.90.0        exportsOnly:true,// Customize how css export names are exported to javascript modules, such as keeping them as is, transforming them to camel case, etc.// type: 'as-is' | 'camel-case' | 'camel-case-only' | 'dashes' | 'dashes-only' | ((name: string) => string)// available since webpack 5.90.4        exportsConvention:'camel-case-only',},'css/auto':{// Generator options for css/auto modules// Avoid generating and loading a stylesheet and only embed exports from css into output javascript files.// type: boolean, available since webpack 5.90.0        exportsOnly:true,// Customize how css export names are exported to javascript modules, such as keeping them as is, transforming them to camel case, etc.// type: 'as-is' | 'camel-case' | 'camel-case-only' | 'dashes' | 'dashes-only' | ((name: string) => string)// available since webpack 5.90.4        exportsConvention:'camel-case-only',// Customize the format of the local class names generated for css modules.// type: string, besides the substitutions at File-level and Module-level in https://webpack.js.org/configuration/output/#template-strings, also include [uniqueName] and [local].// available since webpack 5.90.4        localIdentName:'[uniqueName]-[id]-[local]',},'css/global':{// ditto},'css/module':{// ditto},      json:{// Generator options for json modules// Use `JSON.parse` when the JSON string is longer than 20 characters.        JSONParse:true,},// others…},},};

module.parser

Similar to themodule.generator, you can configure all parsers' options in one place with amodule.parser.

webpack.config.js

module.exports={  module:{    parser:{      asset:{// Parser options for asset modules// The options for data url generator.        dataUrl:{// Asset encoding (defaults to "base64")// type: 'base64' | false          encoding:'base64',// Asset mimetype (getting from file extension by default).// type: string          mimetype:'image/png',},// Emit an output asset from this asset module. This can be set to 'false' to omit emitting e. g. for SSR.// type: boolean        emit:true,// Customize filename for this asset module// type: string | ((pathData: PathData, assetInfo?: AssetInfo) => string)        filename:'static/[path][name][ext]',// Customize publicPath for asset modules, available since webpack 5.28.0// type: string | ((pathData: PathData, assetInfo?: AssetInfo) => string)        publicPath:'https://cdn/assets/',// Emit the asset in the specified folder relative to 'output.path', available since webpack 5.67.0// type: string | ((pathData: PathData, assetInfo?: AssetInfo) => string)        outputPath:'cdn-assets/',},'asset/inline':{// No parser options are supported for this module type yet},'asset/resource':{// ditto},'asset/source':{// ditto},'asset/bytes':{// ditto},      javascript:{// Parser options for javascript modules// e.g, enable parsing of require.ensure syntax        requireEnsure:true,// Set the module to `'strict'` or `'non-strict'` mode. This can affect the module's behavior, as some behaviors differ between strict and non-strict modes.        overrideStrict:'non-strict',},'javascript/auto':{// ditto},'javascript/dynamic':{// ditto},'javascript/esm':{// ditto},      css:{// Parser options for css modules// Enable/disable `@import` at-rules handling, available since webpack 5.97.0// type: booleanimport:true,// Use ES modules named export for css exports, available since webpack 5.90.0// type: boolean        namedExports:true,// Enable/disable url()/image-set()/src()/image() functions handling, available since webpack 5.97.0        url:true,},'css/auto':{// ditto},'css/global':{// ditto},'css/module':{// ditto},// others…},},};

module.parser.css

Configure options for the CSS parser.

module.exports={  module:{    parser:{      css:{// ...        namedExports:true,},},},};

module.parser.css.import

This option enables the handling of@import at-rules in CSS files. When set totrue,@import statements are processed, allowing modular inclusion of styles from other CSS files.

• Type:boolean

• Available: 5.97.0+

• Example:

  module.exports={  module:{    parser:{      css:{import:true,},},},};

  /* reset-styles.css */body{margin: 0;padding: 0;}

  /* styles.css */@import'./reset-styles.css';body{background-color: red;}

To filter specific imports, you can use Webpack's built-inIgnorePlugin. Thefilter option, as available incss-loader, is not supported.

module.parser.css.namedExports

This option enables the use of ES modules named export for CSS exports. When set totrue, the CSS module will export its classes and styles using named exports.

• Type:boolean

• Available: 5.90.0+

• Example:

  module.exports={  module:{    parser:{      css:{        namedExports:true,},},},};

WhennamedExports isfalse for CSS modules, you can retrieve CSS classes using various import methods.Named exports are redirected to improve developer experience (DX), facilitating a smooth transition from default exports to named exports:

import*as stylesfrom'./styles.module.css';import styles1from'./styles.module.css';import{ foo}from'./styles.module.css';console.log(styles.default.foo);// Access via styles.defaultconsole.log(styles.foo);// Access directly from stylesconsole.log(styles1.foo);// Access via default import styles1console.log(foo);// Direct named import

WhennamedExports is enabled (default behavior), you can useonly named exports to import CSS classes.

/* styles.css */.header{color: blue;}.footer{color: green;}

import{ header, footer}from'./styles.module.css';

By enablingnamedExports, you adopt a more modular and maintainable approach to managing CSS in JavaScript projects, leveraging ES module syntax for clearer and more explicit imports.

module.parser.css.url

This option enables or disables the handling of URLs in functions such asurl(),image-set(),src(), andimage() within CSS files. When enabled, these URLs are resolved and processed by webpack.

• Type:boolean

• Available: 5.97.0+

• Example:

  module.exports={  module:{    parser:{      css:{        url:true,},},},};

  /* styles.css */.background{background-image:url('./images/bg.jpg');}.icon{content:image('./icons/star.svg');}

To filter specific imports, you can use Webpack's built-inIgnorePlugin. Thefilter option, as available incss-loader, is not supported.

module.parser.javascript

Configure options for JavaScript parser.

module.exports={  module:{    parser:{      javascript:{// ...        commonjsMagicComments:true,},},},};

It's allowed to configure those options inRule.parser as well to target specific modules.

module.parser.javascript.commonjsMagicComments

Enablemagic comments support for CommonJS.

• Type:boolean

• Available: 5.17.0+

• Example:

  module.exports={  module:{    parser:{      javascript:{        commonjsMagicComments:true,},},},};

Note that onlywebpackIgnore comment is supported at the moment:

const x=require(/* webpackIgnore: true */'x');

module.parser.javascript.dynamicImportFetchPriority

Specify the globalfetchPriority for dynamic import.

• Type:'low' | 'high' | 'auto' | false

• Available: 5.87.0+

• Example:

  module.exports={  module:{    parser:{      javascript:{        dynamicImportFetchPriority:'high',},},},};

module.parser.javascript.dynamicImportMode

Specifies global mode for dynamic import.

• Type:'eager' | 'weak' | 'lazy' | 'lazy-once'

• Available: 5.73.0+

• Example:

  module.exports={  module:{    parser:{      javascript:{        dynamicImportMode:'lazy',},},},};

module.parser.javascript.dynamicImportPrefetch

Specifies global prefetch for dynamic import.

• Type:number | boolean

• Available: 5.73.0+

• Example:

  module.exports={  module:{    parser:{      javascript:{        dynamicImportPrefetch:false,},},},};

module.parser.javascript.dynamicImportPreload

Specifies global preload for dynamic import.

• Type:number | boolean

• Available: 5.73.0+

• Example:

  module.exports={  module:{    parser:{      javascript:{        dynamicImportPreload:false,},},},};

module.parser.javascript.exportsPresence

Specifies the behavior of invalid export names in\"import ... from ...\" and\"export ... from ...\".

• Type:'error' | 'warn' | 'auto' | false

• Available: 5.62.0+

• Example:

  module.exports={  module:{    parser:{      javascript:{        exportsPresence:'error',},},},};

module.parser.javascript.importExportsPresence

Specifies the behavior of invalid export names in\"import ... from ...\".

• Type:'error' | 'warn' | 'auto' | false

• Available: 5.62.0+

• Example:

  module.exports={  module:{    parser:{      javascript:{        importExportsPresence:'error',},},},};

module.parser.javascript.importMeta

Enable or disable evaluatingimport.meta.

• Type:boolean = true

• Available: 5.68.0+

• Example:

  module.exports={  module:{    parser:{      javascript:{        importMeta:false,},},},};

module.parser.javascript.importMetaContext

Enable/disable evaluatingimport.meta.webpackContext.

• Type:boolean

• Available: 5.70.0+

• Example:

  module.exports={  module:{    parser:{      javascript:{        importMetaContext:true,},},},};

module.parser.javascript.overrideStrict

Set the module to'strict' or'non-strict' mode. This can affect the module's behavior, as some behaviors differ between strict and non-strict modes.

• Type:'strict' | 'non-strict'

• Available: 5.93.0+

• Example:

  module.exports={  module:{    parser:{      javascript:{        overrideStrict:'non-strict',},},},};

module.parser.javascript.reexportExportsPresence

Specifies the behavior of invalid export names in\"export ... from ...\". This might be useful to disable during the migration from\"export ... from ...\" to\"export type ... from ...\" when reexporting types in TypeScript.

• Type:'error' | 'warn' | 'auto' | false

• Available: 5.62.0+

• Example:

  module.exports={  module:{    parser:{      javascript:{        reexportExportsPresence:'error',},},},};

module.parser.javascript.url

Enable parsing ofnew URL() syntax.

• Type:boolean = true |'relative'

• Example:

  module.exports={  module:{    parser:{      javascript:{        url:false,// disable parsing of `new URL()` syntax},},},};

The'relative' value formodule.parser.javascript.url is available since webpack5.23.0. When used, webpack would generate relative URLs fornew URL() syntax, i.e., there's no base URL included in the result URL:

<!-- with 'relative' --><imgsrc="c43188443804f1b1f534.svg"/><!-- without 'relative' --><imgsrc="file:///path/to/project/dist/c43188443804f1b1f534.svg"/>

1. This is useful for SSR (Server side rendering) when base URL is not known by server (and it saves a few bytes). To be identical it must also be used for the client build.
2. Also for static site generators, mini-css-plugin and html-plugin, etc. where server side rendering is commonly needed.

module.parser.json

Configure options for json parser.

module.exports={  module:{    parser:{      json:{// options},},},};

module.parser.json.exportsDepth

The depth of json dependency flagged asexportInfo. By default, it is set toInfinity in production mode, and1 in development mode.

• Type:number
• Available:5.98.0+
• Example:

module.exports={  module:{    parser:{      json:{// For example, for the following json// {//   "depth_1": {//     "depth_2": {//       "depth_3": "foo"//     }//   },//   "_depth_1": "bar"// }// when `exportsDepth: 1`, `depth_2` and `depth_3` will not be flagged as `exportInfo`.        exportsDepth:1,},},},};

module.noParse

RegExp[RegExp]function(resource)string[string]

Prevent webpack from parsing any files matching the given regular expression(s). Ignored filesshould not have calls toimport,require,define or any other importing mechanism. This can boost build performance when ignoring large libraries.

noParse can be also used as a way to deliberately prevent expansion of allimport,require,define etc. calls for cases when those calls are unreachable at runtime.For example, when building a project for'browser'target and using a third-party library that was prebuilt for both browser and Node.js and it requires Node.js built-ins e.g.require('os').

module.exports={//...  module:{    noParse:/jquery|lodash|src[\\/]vendor[\\/]somelib/,},};

module.exports={//...  module:{noParse:(content)=>/jquery|lodash|src[\\/]vendor[\\/]somelib/.test(content),},};

module.unsafeCache

booleanfunction (module)

Cache the resolution of module requests. There are a couple of defaults formodule.unsafeCache:

• false ifcache is disabled.
• true ifcache is enabled and the module appears to come from node modules,false otherwise.

webpack.config.js

module.exports={//...  module:{    unsafeCache:false,},};

module.rules

(Rule | undefined | null | false | "" | 0 | "...")[]

An array ofRules which are matched to requests when modules are created. These rules can modify how the module is created. They can apply loaders to the module, or modify the parser.

As of webpack 5.87.0, falsy values such asfalse,undefined,null and0 can be used to conditionally disable a rule.

Rule

object

A Rule can be separated into three parts — Conditions, Results and nested Rules.

Rule Conditions

There are two input values for the conditions:

1. The resource: An absolute path to the file requested. It's already resolved according to theresolve rules.

2. The issuer: An absolute path to the file of the module which requested the resource. It's the location of the import.

Example: When weimport './style.css' withinapp.js, the resource is/path/to/style.css and the issuer is/path/to/app.js.

In a Rule the propertiestest,include,exclude andresource are matched with the resource and the propertyissuer is matched with the issuer.

When using multiple conditions, all conditions must match.

Be careful! The resource is theresolved path of the file, which means symlinked resources are the real pathnot the symlink location. This is good to remember when using tools that symlink packages (likenpm link), common conditions like/node_modules/ may inadvertently miss symlinked files. Note that you can turn off symlink resolving (so that resources are resolved to the symlink path) viaresolve.symlinks.

Rule results

Rule results are used only when the Rule condition matches.

There are two output values of a Rule:

1. Applied loaders: An array of loaders applied to the resource.
2. Parser options: An options object which should be used to create the parser for this module.

These properties affect the loaders:loader,options,use.

For compatibility also these properties:query,loaders.

Theenforce property affects the loader category. Whether it's a normal, pre- or post- loader.

Theparser property affects the parser options.

Nested rules

Nested rules can be specified under the propertiesrules andoneOf.

These rules are evaluated only when the parent Rule condition matches. Each nested rule can contain its own conditions.

The order of evaluation is as follows:

1. The parent rule
2. rules
3. oneOf

Rule.assert

ACondition that allows you to match the import assertion of a dependency and apply specific rules based on the assertion type.

webpack.config.js

module.exports={// ...  module:{    rules:[{// Handles imports with the assertion "assert { type: 'json' }"        assert:{ type:'json'},        loader: require.resolve('./loader-assert.js'),},],},};

index.js

import onefrom'./pkg-1.json' assert{ type:'json'};

In this example,Rule.assert is used to applyloader-assert.js to any module imported with the assertionassert { type: "json" }, ensuring that JSON files are processed correctly.

Rule.compiler

ACondition that allows you to match the child compiler name.

webpack.config.js

module.exports={// ...  name:'compiler',  module:{    rules:[{        test:/a\.js$/,        compiler:'compiler',// Matches the "compiler" name, loader will be applied        use:'./loader',},{        test:/b\.js$/,        compiler:'other-compiler',// Does not match the "compiler" name, loader will NOT be applied        use:'./loader',},],},};

Rule.enforce

string

Possible values:'pre' | 'post'

Specifies the category of the loader. No value means normal loader.

There is also an additional category "inlined loader" which are loaders applied inline of the import/require.

There are two phases that all loaders enter one after the other:

1. Pitching phase: the pitch method on loaders is called in the orderpost, inline, normal, pre. SeePitching Loader for details.
2. Normal phase: the normal method on loaders is executed in the orderpre, normal, inline, post. Transformation on the source code of a module happens in this phase.

All normal loaders can be omitted (overridden) by prefixing! in the request.

All normal and pre loaders can be omitted (overridden) by prefixing-! in the request.

All normal, post and pre loaders can be omitted (overridden) by prefixing!! in the request.

// Disable normal loadersimport{ a}from'!./file1.js';// Disable preloaders and normal loadersimport{ b}from'-!./file2.js';// Disable all loadersimport{ c}from'!!./file3.js';

Inline loaders and! prefixes should not be used as they are non-standard. They may be used by loader generated code.

Rule.exclude

Exclude all modules matching any of these conditions. If you supply aRule.exclude option, you cannot also supply aRule.resource. SeeRule.resource andCondition.exclude for details.

Rule.include

Include all modules matching any of these conditions. If you supply aRule.include option, you cannot also supply aRule.resource. SeeRule.resource andCondition.include for details.

Rule.issuer

ACondition to match against the module that issued the request. In the following example, theissuer for thea.js request would be the path to theindex.js file.

index.js

importAfrom'./a.js';

This option can be used to apply loaders to the dependencies of a specific module or set of modules.

Rule.issuerLayer

Allows to filter/match by layer of the issuer.

webpack.config.js

module.exports={// ...  module:{    rules:[{        issuerLayer:'other-layer',},],},};

Rule.layer

string

Specify the layer in which the module should be placed in. A group of modules could be united in one layer which could then be used insplit chunks,stats orentry options.

webpack.config.js

module.exports={// ...  module:{    rules:[{        test:/module-layer-change/,        layer:'layer',},],},};

Rule.extractSourceMap

boolean = false

Extracts existing source map data from files (from their//# sourceMappingURL comment), useful for preserving the source maps of third-party libraries.

webpack.config.js

module.exports={// ...  module:{    rules:[{        test:/\.m?js$/,        extractSourceMap:true,},],},};

Rule.loader

Rule.loader is a shortcut toRule.use: [ { loader } ]. SeeRule.use andUseEntry.loader for details.

Rule.loaders

Rule.loaders is an alias toRule.use. SeeRule.use for details.

Rule.mimetype

You can match config rules to data uri withmimetype.

webpack.config.js

module.exports={// ...  module:{    rules:[{        mimetype:'application/json',        type:'json',},],},};

application/json,text/javascript,application/javascript,application/node andapplication/wasm are already included by default as mimetype.

Rule.oneOf

An array ofRules from which only the first matching Rule is used when the Rule matches.

webpack.config.js

module.exports={//...  module:{    rules:[{        test:/\.css$/,        oneOf:[{            resourceQuery:/inline/,// foo.css?inline            type:'asset/inline',},{            resourceQuery:/external/,// foo.css?external            type:'asset/resource',},],},],},};

SeeNested rules for more information.

Rule.options / Rule.query

Rule.options andRule.query are shortcuts toRule.use: [ { options } ]. SeeRule.use andUseEntry.options for details.

Rule.parser

An object with parser options. All applied parser options are merged.

Parsers may inspect these options and disable or reconfigure themselves accordingly. Most of the default plugins interpret the values as follows:

• Setting the option tofalse disables the parser.
• Setting the option totrue or leaving itundefined enables the parser.

However, parser plugins may accept more than only a boolean. For example, the internalNodeStuffPlugin can accept an object instead oftrue to add additional options for a particular Rule.

Examples (parser options by the default plugins):

module.exports={//...  module:{    rules:[{//...        parser:{          amd:false,// disable AMD          commonjs:false,// disable CommonJS          system:false,// disable SystemJS          harmony:false,// disable ES2015 Harmony import/export          requireInclude:false,// disable require.include          requireEnsure:false,// disable require.ensure          requireContext:false,// disable require.context          browserify:false,// disable special handling of Browserify bundles          requireJs:false,// disable requirejs.*          node:false,// disable __dirname, __filename, module, require.extensions, require.main, etc.          commonjsMagicComments:false,// disable magic comments support for CommonJS          node:{},// reconfigure node layer on module level          worker:['default from web-worker','...'],// Customize the WebWorker handling for javascript files, "..." refers to the defaults.},},],},};

IfRule.type is anasset thenRules.parser option may be an object or a function that describes a condition whether to encode file contents to Base64 or emit it as a separate file into the output directory.

IfRule.type is anasset orasset/inline thenRule.generator option may be an object that describes the encoding of the module source or a function that encodes module's source by a custom algorithm.

SeeAsset Modules guide for additional information and use cases.

Rule.parser.dataUrlCondition

object = { maxSize number = 8096 }function (source, { filename, module }) => boolean

If a module source size is less thanmaxSize then module will be injected into the bundle as a Base64-encoded string, otherwise module file will be emitted into the output directory.

webpack.config.js

module.exports={//...  module:{    rules:[{//...        parser:{          dataUrlCondition:{            maxSize:4*1024,},},},],},};

When a function is given, returningtrue tells webpack to inject the module into the bundle as Base64-encoded string, otherwise module file will be emitted into the output directory.

webpack.config.js

module.exports={//...  module:{    rules:[{//...        parser:{dataUrlCondition:(source,{ filename, module})=>{const content= source.toString();return content.includes('some marker');},},},],},};

Rule.generator

Rule.generator.dataUrl

object = { encoding string = 'base64' | false, mimetype string = undefined | false }function (content, { filename, module }) => string

WhenRule.generator.dataUrl is used as an object, you can configure two properties:

• encoding: When set to'base64', module source will be encoded using Base64 algorithm. Settingencoding to false will disable encoding.
• mimetype: A mimetype for data URI. Resolves from module resource extension by default.

webpack.config.js

module.exports={//...  module:{    rules:[{//...        generator:{          dataUrl:{            encoding:'base64',            mimetype:'mimetype/png',},},},],},};

When used a a function, it executes for every module and must return a data URI string.

module.exports={//...  module:{    rules:[{//...        generator:{dataUrl:(content)=>{const svgToMiniDataURI=require('mini-svg-data-uri');if(typeof content!=='string'){              content= content.toString();}returnsvgToMiniDataURI(content);},},},],},};

Rule.generator.emit

Opt out of writing assets fromAsset Modules, you might want to use it in Server side rendering cases.

• Type:boolean = true

• Available:5.25.0+

• Example:

  module.exports={// …  module:{    rules:[{        test:/\.png$/i,        type:'asset/resource',        generator:{          emit:false,},},],},};

Rule.generator.filename

The same asoutput.assetModuleFilename but for specific rule. Overridesoutput.assetModuleFilename and works only withasset andasset/resource module types.

webpack.config.js

module.exports={//...  output:{    assetModuleFilename:'images/[hash][ext][query]',},  module:{    rules:[{        test:/\.png$/,        type:'asset/resource',},{        test:/\.html$/,        type:'asset/resource',        generator:{          filename:'static/[hash][ext]',},},],},};

Rule.generator.publicPath

CustomizepublicPath for specific Asset Modules.

• Type:string | ((pathData: PathData, assetInfo?: AssetInfo) => string)
• Available:5.28.0+

module.exports={//...  output:{    publicPath:'static/',},  module:{    rules:[{        test:/\.png$/i,        type:'asset/resource',        generator:{          publicPath:'assets/',},},],},};

Rule.generator.outputPath

Emit the asset in the specified folder relative to 'output.path'. This should only be needed when custom 'publicPath' is specified to match the folder structure there.

• Type:string | ((pathData: PathData, assetInfo?: AssetInfo) => string)
• Available:5.67.0+

module.exports={//...  output:{    publicPath:'static/',},  module:{    rules:[{        test:/\.png$/i,        type:'asset/resource',        generator:{          publicPath:'https://cdn/assets/',          outputPath:'cdn-assets/',},},],},};

Rule.resource

ACondition matched with the resource. See details inRule conditions.

Rule.resourceQuery

ACondition matched with the resource query. This option is used to test against the query section of a request string (i.e. from the question mark onwards). If you were toimport Foo from './foo.css?inline', the following condition would match:

webpack.config.js

module.exports={//...  module:{    rules:[{        test:/\.css$/,        resourceQuery:/inline/,        type:'asset/inline',},],},};

Rule.parser.parse

function(input) => string | object

IfRule.type is set to'json' thenRules.parser.parse option may be a function that implements custom logic to parse module's source and convert it to a JavaScriptobject. It may be useful to importtoml,yaml and other non-JSON files as JSON, without specific loaders:

webpack.config.js

const toml=require('toml');module.exports={//...  module:{    rules:[{        test:/\.toml/,        type:'json',        parser:{          parse: toml.parse,},},],},};

Rule.rules

An array ofRules that is also used when the Rule matches.

SeeNested rules for more information.

Rule.scheme

Match the used schema, e.g.,data,http.

• Type:string | RegExp | ((value: string) => boolean) | RuleSetLogicalConditions | RuleSetCondition[]
• Available:5.38.0+

webpack.config.js

module.exports={  module:{    rules:[{        scheme:'data',        type:'asset/resource',},],},};

Rule.sideEffects

bool

Indicate what parts of the module contain side effects. SeeTree Shaking for details.

Rule.test

Include all modules that pass test assertion. If you supply aRule.test option, you cannot also supply aRule.resource. SeeRule.resource andCondition for details.

Rule.type

string

Possible values:'javascript/auto' | 'javascript/dynamic' | 'javascript/esm' | 'json' | 'webassembly/sync' | 'webassembly/async' | 'asset' | 'asset/source' | 'asset/resource' | 'asset/inline' | 'asset/bytes' | 'css' | 'css/auto' | 'css/module' | 'css/global'

Rule.type sets the type for a matching module. This prevents defaultRules and their default importing behaviors from occurring. For example, if you want to load a.json file through a custom loader, you'd need to set thetype tojavascript/auto to bypass webpack's built-in json importing.

webpack.config.js

module.exports={//...  module:{    rules:[//...{        test:/\.json$/,        type:'javascript/auto',        loader:'custom-json-loader',},],},};

SeeAsset Modules guide for more aboutasset* type.

css/auto

See use case ofcss/auto module typehere. Make sure to enableexperiments.css to usecss/auto.

module.exports={  target:'web',  mode:'development',  experiments:{    css:true,},  module:{    rules:[{        test:/\.less$/,        use:'less-loader',        type:'css/auto',},],},};

Rule.use

[UseEntry]function(info)

Starting with webpack 5.87.0 falsy values such asundefinednull can be used to conditionally disable specific use entry.

[UseEntry]

Rule.use can be an array ofUseEntry which are applied to modules. Each entry specifies a loader to be used.

Passing a string (i.e.use: [ 'style-loader' ]) is a shortcut to the loader property (i.e.use: [ { loader: 'style-loader '} ]).

Loaders can be chained by passing multiple loaders, which will be applied from right to left (last to first configured).

webpack.config.js

module.exports={//...  module:{    rules:[{//...        use:['style-loader',{            loader:'css-loader',            options:{              importLoaders:1,},},{            loader:'less-loader',            options:{              noIeCompat:true,},},],},],},};

function(info)

Rule.use can also be a function which receives the object argument describing the module being loaded, and must return an array ofUseEntry items.

Theinfo object parameter has the following fields:

• compiler: The current webpack compiler (can be undefined)
• issuer: The path to the module that is importing the module being loaded
• realResource: Always the path to the module being loaded
• resource: The path to the module being loaded, it is usually equal torealResource except when the resource name is overwritten via!=! in request string

The same shortcut as an array can be used for the return value (i.e.use: [ 'style-loader' ]).

webpack.config.js

module.exports={//...  module:{    rules:[{use:(info)=>[{            loader:'custom-svg-loader',},{            loader:'svgo-loader',            options:{              plugins:[{                  cleanupIDs:{                    prefix:basename(info.resource),},},],},},],},],},};

SeeUseEntry for details.

Rule.resolve

Resolving can be configured on module level. See all available options onresolve configuration page.All applied resolve options get deeply merged with higher levelresolve.

For example, let's imagine we have an entry in./src/index.js,./src/footer/default.js and a./src/footer/overridden.js to demonstrate the module level resolve.

./src/index.js

import footerfrom'footer';console.log(footer);

./src/footer/default.js

exportdefault'default footer';

./src/footer/overridden.js

exportdefault'overridden footer';

webpack.js.org

module.exports={  resolve:{    alias:{      footer:'./footer/default.js',},},};

When creating a bundle with this configuration,console.log(footer) will output 'default footer'. Let's setRule.resolve for.js files, and aliasfooter tooverridden.js.

webpack.js.org

module.exports={  resolve:{    alias:{      footer:'./footer/default.js',},},  module:{    rules:[{        resolve:{          alias:{            footer:'./footer/overridden.js',},},},],},};

When creating a bundle with updated configuration,console.log(footer) will output 'overridden footer'.

resolve.fullySpecified

boolean = true

When enabled, you should provide the file extension whenimporting a module in.mjs files or any other.js files when their nearest parentpackage.json file contains a"type" field with a value of"module", otherwise webpack would fail the compiling with aModule not found error. And webpack won't resolve directories with filenames defined in theresolve.mainFiles, you have to specify the filename yourself.

webpack.config.js

module.exports={// ...  module:{    rules:[{        test:/\.m?js$/,        resolve:{          fullySpecified:false,// disable the behaviour},},],},};

resolve.fullySpecified doesn't affect requests frommainFields,aliasFields oraliases.

Rule.with

ACondition that allows you to match the imports based on specific conditions provided with thewith keyword, enabling different rules to be applied based on the content type.

webpack.config.js

module.exports={// ...  module:{    rules:[{// Handles imports with the condition "with { type: 'json' }"with:{ type:'json'},        loader: require.resolve('./loader-assert.js'),},],},};

index.js

import onefrom'./pkg-1.json'with{ type:'json'};

In this example,Rule.with is used to applyloader-assert.js to any module imported with the conditionwith { type: "json" }.

Condition

Conditions can be one of these:

• A string: To match the input must start with the provided string. I. e. an absolute directory path, or absolute path to the file.
• A RegExp: It's tested with the input.
• A function: It's called with the input and must return a truthy value to match.
• An array of Conditions: At least one of the Conditions must match.
• An object: All properties must match. Each property has a defined behavior.

{ and: [Condition] }: All Conditions must match.

{ or: [Condition] }: Any Condition must match.

{ not: [Condition] }: All Conditions must NOT match.

Example:

const path=require('path');module.exports={//...  module:{    rules:[{        test:/\.css$/,        include:[// will include any paths relative to the current directory starting with `app/styles`// e.g. `app/styles.css`, `app/styles/styles.css`, `app/stylesheet.css`          path.resolve(__dirname,'app/styles'),// add an extra slash to only include the content of the directory `vendor/styles/`          path.join(__dirname,'vendor/styles/'),],},],},};

UseEntry

objectfunction(info)

object

It must have aloader property being a string. It is resolved relative to the configurationcontext with the loader resolving options (resolveLoader).

It can have anoptions property being a string or object. This value is passed to the loader, which should interpret it as loader options.

For compatibility aquery property is also possible, which is an alias for theoptions property. Use theoptions property instead.

Note that webpack needs to generate a unique module identifier from the resource and all loaders including options. It tries to do this with aJSON.stringify of the options object. This is fine in 99.9% of cases, but may be not unique if you apply the same loaders with different options to the resource and the options have same stringified values.

It also breaks if the options object cannot be stringified (i.e. circular JSON). Because of this you can have aident property in the options object which is used as unique identifier.

webpack.config.js

module.exports={//...  module:{    rules:[{        loader:'css-loader',        options:{          modules:true,},},],},};

function(info)

AUseEntry can also be a function which receives the object argument describing the module being loaded, and must return a non-functionUseEntry object. This can be used to vary the loader options on a per-module basis.

Theinfo object parameter has the following fields:

• compiler: The current webpack compiler (can be undefined)
• issuer: The path to the module that is importing the module being loaded
• realResource: Always the path to the module being loaded
• resource: The path to the module being loaded, it is usually equal torealResource except when the resource name is overwritten via!=! in request string

webpack.config.js

module.exports={//...  module:{    rules:[{        test:/\.svg$/,        type:'asset',use:(info)=>({          loader:'svgo-loader',          options:{            plugins:[{                cleanupIDs:{ prefix:basename(info.resource)},},],},}),},],},};

Module Contexts

These options describe the default settings for the context created when a dynamic dependency is encountered.

Example for anunknown dynamic dependency:require.

Example for anexpr dynamic dependency:require(expr).

Example for anwrapped dynamic dependency:require('./templates/' + expr).

Here are the available options with theirdefaults:

webpack.config.js

module.exports={//...  module:{    exprContextCritical:true,    exprContextRecursive:true,    exprContextRegExp:false,    exprContextRequest:'.',    unknownContextCritical:true,    unknownContextRecursive:true,    unknownContextRegExp:false,    unknownContextRequest:'.',    wrappedContextCritical:false,    wrappedContextRecursive:true,    wrappedContextRegExp:/.*/,    strictExportPresence:false,},};

strictExportPresence is deprecated in favor ofexportsPresence option.

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