Command Line Interface (CLI)

Command Line Interface (CLI)

webpack provides a Command Line Interface (CLI) to configure and interact with your build. This is mostly useful in case of early prototyping, profiling, writing npm scripts or personal customization of the build.

For proper usage and easy distribution of this configuration, webpack can be configured with webpack.config.js. Any parameters sent to the CLI will map to a corresponding parameter in the config file.

Have a look at the installation guide unless you have webpack already running.

The new CLI for webpack is under development. New features are being added such as the --init flag. Check it out!

Usage with config file

webpack [--config webpack.config.js]

See configuration for the options in the configuration file.

Usage without config file

webpack <entry> [<entry>] <output>

<entry>

A filename or a set of named filenames which act as the entry point to build your project. You can pass multiple entries (every entry is loaded on startup). If you pass a pair in the form <name>=<request> you can create an additional entry point. It will be mapped to the configuration option entry.

<output>

A path and filename for the bundled file to be saved in. It will be mapped to the configuration options output.path and output.filename.

Example

If your project structure is as follows -

.
├── dist
├── index.html
└── src
    ├── index.js
    ├── index2.js
    └── others.js

webpack src/index.js dist/bundle.js

This will bundle your source code with entry as index.js and the output bundle file will have a path of dist and the filename will be bundle.js

    | Asset     | Size    | Chunks      | Chunk Names |
    |-----------|---------|-------------|-------------|
    | bundle.js | 1.54 kB | 0 [emitted] | index       |
    [0] ./src/index.js 51 bytes {0} [built]
    [1] ./src/others.js 29 bytes {0} [built]

webpack index=./src/index.js entry2=./src/index2.js dist/bundle.js

This will form the bundle with both the files as separate entry points.

    | Asset     | Size    | Chunks        | Chunk Names   |
    |-----------|---------|---------------|---------------|
    | bundle.js | 1.55 kB | 0,1 [emitted] | index, entry2 |
    [0] ./src/index.js 51 bytes {0} [built]
    [0] ./src/index2.js 54 bytes {1} [built]
    [1] ./src/others.js 29 bytes {0} {1} [built]

Common Options

List all of the options available on the cli

webpack --help
webpack -h

Build source using a config file

Specifies a different configuration file to pick up. Use this if you want to specify something different than webpack.config.js, which is the default.

webpack --config example.config.js

Specify build environment

Send environment variable to be used in webpack config file.

webpack --env.production    # sets production to true
webpack --env.platform=web  # sets platform to "web"

Print result of webpack as a JSON

webpack --json
webpack --json > stats.json

In every other case, webpack prints out a set of stats showing bundle, chunk and timing details. Using this option the output can be a JSON object. This response is accepted by webpack's analyse tool, or chrisbateman's webpack-visualizer, or th0r's webpack-bundle-analyzer. The analyse tool will take in the JSON and provide all the details of the build in graphical form.

Output Options

This set of options allows you to manipulate certain output parameters of your build.

Example Usage

webpack index=./src/index.js index2=./src/index2.js --output-path='./dist' --output-filename='[name][hash].bundle.js'

| Asset                                | Size    | Chunks      | Chunk Names   |
|--------------------------------------|---------|-------------|---------------|
| index2740fdca26e9348bedbec.bundle.js |  2.6 kB | 0 [emitted] | index2        |
| index740fdca26e9348bedbec.bundle.js  | 2.59 kB | 1 [emitted] | index         |
    [0] ./src/others.js 29 bytes {0} {1} [built]
    [1] ./src/index.js 51 bytes {1} [built]
    [2] ./src/index2.js 54 bytes {0} [built]

webpack.js index=./src/index.js index2=./src/index2.js --output-path='./dist' --output-filename='[name][hash].bundle.js' --devtool source-map --output-source-map-filename='[name]123.map'

| Asset                                | Size    | Chunks      | Chunk Names   |
|--------------------------------------|---------|-------------|---------------|
| index2740fdca26e9348bedbec.bundle.js | 2.76 kB | 0 [emitted] | index2        |
|  index740fdca26e9348bedbec.bundle.js | 2.74 kB | 1 [emitted] | index         |
|                        index2123.map | 2.95 kB | 0 [emitted] | index2        |
|                         index123.map | 2.95 kB | 1 [emitted] | index         |
    [0] ./src/others.js 29 bytes {0} {1} [built]
    [1] ./src/index.js 51 bytes {1} [built]
    [2] ./src/index2.js 54 bytes {0} [built]

Debug Options

This set of options allows you to better debug the application containing assets compiled with webpack

Module Options

These options allow you to bind modules as allowed by webpack

Watch Options

These options makes the build watch for changes in files of the dependency graph and perform the build again.

Optimize Options

These options allow you to manipulate optimisations for a production build using webpack

Resolve Options

These allow you to configure the webpack resolver with aliases and extensions.

Stats Options

These options allow webpack to display various stats and style them differently in the console output.

Advanced Options

Shortcuts

Profiling

This option profiles the compilation and includes this information in the stats output. It gives you an in depth idea of which step in the compilation is taking how long. This can help you optimise your build in a more informed manner.

webpack --profile

30ms building modules
1ms sealing
1ms optimizing
0ms basic module optimization
1ms module optimization
1ms advanced module optimization
0ms basic chunk optimization
0ms chunk optimization
1ms advanced chunk optimization
0ms module and chunk tree optimization
1ms module reviving
0ms module order optimization
1ms module id optimization
1ms chunk reviving
0ms chunk order optimization
1ms chunk id optimization
10ms hashing
0ms module assets processing
13ms chunk assets processing
1ms additional chunk assets processing
0ms recording
0ms additional asset processing
26ms chunk asset optimization
1ms asset optimization
6ms emitting

Further Reading

• Analyzing Build Statistics
• Three simple ways to inspect a webpack bundle
• Optimising your application bundle size with webpack
• Analyzing & optimizing your webpack bundle
• Analysing and minimising the size of client side bundle with webpack and source-map-explorer