Output

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Options affecting the output of the compilation. output options tell webpack how to write the compiled files to disk. Note, that while there can be multiple entry points, only one output configuration is specified.

If you use any hashing ([hash] or [chunkhash]), make sure to have a consistent ordering of modules. Use the OccurrenceOrderPlugin or recordsPath.

Usage

The minimum requirements for the output property in your webpack config is to set its value to an object including the following two things :

Your preferred filename of the compiled file: // main.js || bundle.js || index.js

An output.path as an absolute path for what directory you prefer it to go in once bundled.

webpack.config.js

const config = {
  output: {
    filename: 'bundle.js',
    path: '/home/proj/public/assets'
  }
};

module.exports = config;

Options

The following is a list of values you can pass to the output property.

output.chunkFilename

The filename of non-entry chunks as a relative path inside the output.path directory.

[id] is replaced by the id of the chunk.

[name] is replaced by the name of the chunk (or with the id when the chunk has no name).

[hash] is replaced by the hash of the compilation.

[chunkhash] is replaced by the hash of the chunk.

output.crossOriginLoading

This option enables cross-origin loading of chunks.

Possible values are:

false - Disable cross-origin loading.

"anonymous" - Cross-origin loading is enabled. When using anonymous no credentials will be sent with the request.

"use-credentials" - Cross-origin loading is enabled and credentials will be send with the request.

For more information on cross-origin loading see MDN

Default: false

see also library

see also Development Tools

output.devtoolLineToLine

Enable line-to-line mapped mode for all/specified modules. Line-to-line mapped mode uses a simple SourceMap where each line of the generated source is mapped to the same line of the original source. It's a performance optimization. Only use it if your performance needs to be better and you are sure that input lines match which generated lines.

true enables it for all modules (not recommended)

An object {test, include, exclude} similar to module.loaders enables it for specific files.

Default: false

output.filename

Specifies the name of each output file on disk. You must not specify an absolute path here! The output.path option determines the location on disk the files are written. filename is used solely for naming the individual files.

single entry

{
  entry: './src/app.js',
  output: {
    filename: 'bundle.js',
    path: __dirname + '/build'
  }
}

// writes to disk: ./build/bundle.js

multiple entries

If your configuration creates more than a single "chunk" (as with multiple entry points or when using plugins like CommonsChunkPlugin), you should use substitutions to ensure that each file has a unique name.

[name] is replaced by the name of the chunk.

[hash] is replaced by the hash of the compilation.

[chunkhash] is replaced by the hash of the chunk.

{
  entry: {
    app: './src/app.js',
    search: './src/search.js'
  },
  output: {
    filename: '[name].js',
    path: __dirname + '/build'
  }
}

// writes to disk: ./build/app.js, ./build/search.js

output.hotUpdateChunkFilename

The filename of the Hot Update Chunks. They are inside the output.path directory.

[id] is replaced by the id of the chunk.

[hash] is replaced by the hash of the compilation. (The last hash stored in the records)

Default: "[id].[hash].hot-update.js"

output.hotUpdateFunction

The JSONP function used by webpack for async loading of hot update chunks.

Default: "webpackHotUpdate"

output.hotUpdateMainFilename

The filename of the Hot Update Main File. It is inside the output.path directory.

[hash] is replaced by the hash of the compilation. (The last hash stored in the records)

Default: "[hash].hot-update.json"

output.jsonpFunction

The JSONP function used by webpack for async loading of chunks.

A shorter function may reduce the file size a bit. Use a different identifier when having multiple webpack instances on a single page.

Default: "webpackJsonp"

output.library

If set, export the bundle as library. output.library is the name.

Use this if you are writing a library and want to publish it as single file.

output.libraryTarget

Which format to export the library:

"var" - Export by setting a variable: var Library = xxx (default)

"this" - Export by setting a property of this: this["Library"] = xxx

"commonjs" - Export by setting a property of exports: exports["Library"] = xxx

"commonjs2" - Export by setting module.exports: module.exports = xxx

"amd" - Export to AMD (optionally named - set the name via the library option)

"umd" - Export to AMD, CommonJS2 or as property in root

Default: "var"

If output.library is not set, but output.libraryTarget is set to a value other than var, every property of the exported object is copied (Except amd, commonjs2 and umd).

output.path

The output directory as an absolute path (required).

[hash] is replaced by the hash of the compilation.

config.js

output: {
    path: "/home/proj/public/assets",
    publicPath: "/assets/"
}

index.html

<head>
  <link href="/assets/spinner.gif"/>
</head>

And a more complicated example of using a CDN and hashes for assets.

config.js

output: {
    path: "/home/proj/cdn/assets/[hash]",
    publicPath: "http://cdn.example.com/assets/[hash]/"
}

Note: In cases when the eventual publicPath of output files isn't known at compile time, it can be left blank and set dynamically at runtime in the entry point file. If you don't know the publicPath while compiling, you can omit it and set __webpack_public_path__ on your entry point.

 __webpack_public_path__ = myRuntimePublicPath

// rest of your application entry

output.sourceMapFilename

The filename of the SourceMaps for the JavaScript files. They are inside the output.path directory.

[file] is replaced by the filename of the JavaScript file.

[id] is replaced by the id of the chunk.

[hash] is replaced by the hash of the compilation.

Default: "[file].map"


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