README

# Speed Measure Plugin (for webpack)

The first step to optimising your webpack build speed, is to know where to focus your attention.

This plugin measures your webpack build speed, giving an output like this:

## Install

npm install --save-dev speed-measure-webpack-plugin

or

yarn add -D speed-measure-webpack-plugin

## Requirements

SMP requires at least Node v6. But otherwise, accepts all webpack versions (1, 2, 3, and 4).

## Usage

Change your webpack config from

const webpackConfig = {
plugins: [
new MyPlugin(),
new MyOtherPlugin()
]
}

to

const SpeedMeasurePlugin = require("speed-measure-webpack-plugin");
const smp = new SpeedMeasurePlugin();
const webpackConfig = smp.wrap({
plugins: [
new MyPlugin(),
new MyOtherPlugin()
]
});

and you're done! SMP will now be printing timing output to the console by default.

Check out the examples folder for some more examples.

## Options

Pass these into the constructor, as an object:

const smp = new SpeedMeasurePlugin(options);

### <tt>options.disable</tt>

Type: `Boolean`
Default: `false`

If truthy, this plugin does nothing at all.

`{ disable: !process.env.MEASURE }` allows opt-in measurements with `MEASURE=true npm run build`.

### <tt>options.outputFormat</tt>

Type: `String|Function`
Default: `"human"`

Determines in what format this plugin prints its measurements

- `"json"` - produces a JSON blob
- `"human"` - produces a human readable output
- `"humanVerbose"` - produces a more verbose version of the human readable output
- If a function, it will call the function with the JSON blob, and output the response

### <tt>options.outputTarget</tt>

Type: `String|Function`
Default: `console.log`

- If a string, it specifies the path to a file to output to.
- If a function, it will call the function with the output as the first parameter

### <tt>options.pluginNames</tt>

Type: `Object`
Default: `{}`

By default, SMP derives plugin names through `plugin.constructor.name`. For some plugins this doesn't work (or you may want to override this default). This option takes an object of `pluginName: PluginConstructor`, e.g.

const uglify = new UglifyJSPlugin();
const smp = new SpeedMeasurePlugin({
pluginNames: {
customUglifyName: uglify
}
});
const webpackConfig = smp.wrap({
plugins: [
uglify
]
});

### <tt>options.granularLoaderData</tt> _(experimental)_

Type: `Boolean`
Default: `false`

By default, SMP measures loaders in groups. If truthy, this plugin will give per-loader timing information.

This flag is experimental. Some loaders will have inaccurate results:

- loaders using separate processes (e.g. `thread-loader`)
- loaders emitting file output (e.g. `file-loader`)

We will find solutions to these issues before removing the _(experimental)_ flag on this option.

## FAQ

### What does general output time mean?

This tends to be down to webpack reading in from the file-system, but in general it's anything outside of what SMP can actually measure.

### What does modules without loaders mean?

It means vanilla JS files, which webpack can handle out of the box.

## Contributing

Contributors are welcome! 😊

Please check out the CONTRIBUTING.md.

## Migrating

SMP follows semver. If upgrading a major version, you can consult the migration guide.

## License

MIT