Command Line Interface

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 configuration file.

Read the installation guide if you don't already have webpack and CLI installed.

Commands

webpack-cli offers a variety of commands to make working with webpack easy. By default webpack ships with

| Command | Alias | Description | | --------- | ----- | ------------------------------------------------------ | | init | c | Initialize a new webpack configuration | | migrate | m | Migrate a configuration to a new version | | loader | l | Scaffold a loader repository | | plugin | p | Scaffold a plugin repository | | info | i | Outputs information about your system and dependencies | | serve | s | Run the webpack Dev Server |

Flags

webpack-cli offers a variety of commands to make working with webpack easy. By default webpack ships with the following flags:

Note: These are the flags with webpack v4, starting v5 CLI also supports core flags

| Flag / Alias | Type | Description | | ------------------- | --------------- | -------------------------------------------------------------------------------------------------------------- | | --entry | string[] | The entry point(s) of your application e.g. ./src/main.js | | --config, -c | string[] | Provide path to a webpack configuration file e.g. ./webpack.config.js | | --config-name | string[] | Name of the configuration to use | | --name | string[] | Name of the configuration. Used when loading multiple configurations | | --color | boolean | Enable colors on console | | --no-color | boolean | Disables colors on console | | --merge, -m | boolean | Merge two or more configurations using webpack-merge e.g. -c ./webpack.config.js -c ./webpack.test.config.js | | --env | string[] | Environment passed to the configuration when it is a function | | --progress | boolean, string | Print compilation progress during build | | --help | boolean | Outputs list of supported flags and commands | | --output-path, -o | string | Output location of the file generated by webpack e.g. ./dist | | --target, -t | string[] | Sets the build target | | --watch, -w | boolean | Watch for file changes | | --hot, -h | boolean | Enables Hot Module Replacement | | --no-hot | boolean | Disables Hot Module Replacement | | --devtool, -d | string | Controls if and how source maps are generated. | | --prefetch | string | Prefetch this request | | --json, -j | boolean, string | Prints result as JSON or store it in a file | | --mode | string | Defines the mode to pass to webpack | | --version, -v | boolean | Get current version | | --stats | boolean, string | It instructs webpack on how to treat the stats | | --no-stats | boolean | Disables stats output | | --analyze | boolean | It invokes webpack-bundle-analyzer plugin to get bundle information |

Negated Flags

| Flag | Description | | ---------- | ------------------------------------------------------------- | | --no-color | Disabled any color on the console | | --no-hot | Disabled hot reloading if you have it enabled via your config | | --no-stats | Disables any compilation stats emitted by webpack |

Core Flags

Starting CLI v4 and webpack v5, CLI imports the entire configuration schema from webpack core to allow tuning almost every configuration option from the command line.

Here's the list of all the core flags supported by webpack v5 with CLI v4 - link

For example if you want to enable performance hints in your project you'd use this option in configuration, with core flags you can do -

webpack --performance-hints warning

Usage

With configuration file

webpack [--config webpack.config.js]

See configuration for the options in the configuration file.

Without configuration file

webpack <entry> [<entry>] -o <output-path>

example

webpack --entry ./first.js --entry ./second.js --output-path /build

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

Example

If your project structure is as follows -

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

webpack ./src/index.js -o dist

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

asset main.js 142 bytes [compared for emit] [minimized] (name: main)
./src/index.js 30 bytes [built] [code generated]
./src/others.js 1 bytes [built] [code generated]
webpack 5.1.0 compiled successfully in 187 ms

webpack ./src/index.js ./src/others2.js -o dist/

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

asset main.js 142 bytes [compared for emit] [minimized] (name: main)
./src/index.js 30 bytes [built] [code generated]
./src/others2.js 1 bytes [built] [code generated]
./src/others.js 1 bytes [built] [code generated]
webpack 5.1.0 compiled successfully in 198 ms

Default Configurations

CLI will look for some default configurations in the path of your project, here are the config files picked up by CLI.

If no mode is supplied via flags or config then this is the lookup order in increasing order

example - config file lookup will be in order of .webpack/webpack.config.development.js > webpack.config.development.js > webpack.config.js

'webpack.config',
'webpack.config.dev',
'webpack.config.development',
'webpack.config.prod',
'webpack.config.production',
'.webpack/webpack.config',
'.webpack/webpack.config.none',
'.webpack/webpack.config.dev',
'.webpack/webpack.config.development',
'.webpack/webpack.config.prod',
'.webpack/webpack.config.production',
'.webpack/webpackfile',

If mode is supplied, say production then config looking order will be -

.webpack/webpack.config.production.* > .webpack/webpack.config.prod.* > webpack.config.production.* > webpack.config.prod.* > webpack.config.*

Common Options

Note that Command Line Interface has a higher precedence for the arguments you use it with than your configuration file. For instance, if you pass --mode="production" to webpack CLI and your configuration file uses development, production will be used.

List all of the commands and flags available on the cli

webpack --help

Show help for a single command or flag

webpack --help <command>
webpack --help --<flag>

Build source using a configuration file

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

webpack --config example.config.js

Print result of webpack as a JSON

webpack --json

If you want to store stats as json instead of printing it, you can use -

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.

Environment Options

When the webpack configuration exports a function, an "environment" may be passed to it.

webpack --env production    # sets env.production == true

The --env argument accepts multiple values:

| Invocation | Resulting environment | | --------------------------------------------- | --------------------------------------- | | webpack --env prod | { prod: true } | | webpack --env prod --env min | { prod: true, min: true } | | webpack --env platform=app --env production | { platform: "app", production: true } |

See the environment variables guide for more information on its usage.

Configuration Options

| Parameter | Explanation | Input type | Default | | --------------- | -------------------------------------------------------------- | ---------- | --------------------------------------------------- | | --config | Path to the configuration file | string | Default Configs | | --config-name | Name of the configuration to use | string | | --env | Environment passed to the configuration, when it is a function | | | --mode | Mode to use | string | 'production' |

Analyzing Bundle

You can also use webpack-bundle-analyzer to analyze your output bundles emitted by webpack. You can use --analyze flag to invoke it via CLI.

webpack --analyze

Make sure you have webpack-bundle-analyzer installed in your project else CLI will prompt you to install it.

Progress

To check the progress of any webpack compilation you can use the --progress flag.

webpack --progress

To collect profile data for progress steps you can pass profile as value to --progress flag.

webpack --progress=profile

Pass CLI arguments to Node.js

To pass arguments directly to Node.js process, you can use the NODE_OPTIONS option.

For example, to increase the memory limit of Node.js process to 4 GB

NODE_OPTIONS="--max-old-space-size=4096" webpack

Also, you can pass multiple options to Node.js process

NODE_OPTIONS="--max-old-space-size=4096 -r /path/to/preload/file.js" webpack

Exit codes and their meanings

| Exit Code | Description | | --------- | -------------------------------------------------- | | 0 | Success | | 1 | Errors from webpack | | 2 | Configuration/options problem or an internal error |