ember-unused-components

This script searches for unused components in your Ember project. It supports:

• classic structure,
• POD structure,
• Module Unification structure,
• {{curly-braces}} syntax,
• <AngleBrackets> syntax (also nested ones like <Angle::MyBrackets>),
• ember-light-table's way of defining cellComponent: 'component-name' and component: 'component-name'
• (component "component-name") helper used in templates
• ignoring files,
• whitelisting components unused temporary,
• addons,
• and components being used in addons with --includeAddons option.

It also has a very interesting statistics module.

Installation

$ yarn add -D ember-unused-components

or

$ npm install ember-unused-components --save-dev

Usage

Run in your app root directory:

$ ./node_modules/.bin/ember-unused-components

or

$ npx ember-unused-components

Expected output (simplified):

 No. of components: 277
 No. of unused components: 2 (7.22%)

 Unused components:
  - app/app-tab-panel
  - user/user-birthday

If you feel like there are too many components listed then check Configuration Section.

Stats

Make sure to try optional parameter --stats so you'll see some interesting stuff:

$ npx ember-unused-components --stats

 No. of components: 304
 No. of unused components: 8 (2.63%)

 Unused components:
  - report-header
  - report-row-title
  - reports-settings-dropdown
  - ui-checkbox-list
  - ui-manage-screen-title
  - ui-phone/-body/-message
  - ui-table/-cell-currency
  - ui-table/-cell-date

 The most used component: ui-form-button (101 occurrences)
 The number of components used just once: 171 (56.25%)
 Usage of {{curly-braces}} vs <AngleBrackets> syntax: 509 (56.81%) vs 387 (43.19%)
 Usage of (component "component-name") helper in templates: 70
 Usage in JS files (e.g. through `import` or ELT): 63

Occurrences

You can also print all occurrences of components that were found. Use --occurrences or --o:

$ npx ember-unused-components --occurrences

// simplified

user-avatar:

   > ./app/templates/components/user-card.hbs
    - <UserAvatar @src={{_imageSource}} />

welcome-page:

   > ./app/templates/application.hbs
    - {{welcome-page}}

[EXPERIMENTAL] Searching components contained in other packages

You can also print all occurrences of components that were found in included addons. Use --includeAddons to include all found addons, or includeAddons=company-* to only include addons that match company-*

$ npx ember-unused-components --occurrences --includeAddons=company-*

// simplified

[company-buttons] button-a:

   > ./app/templates/components/user-card.hbs
    - <ButtonA>Button Text</ButtonA>

welcome-page:

   > ./app/templates/application.hbs
    - {{welcome-page}}

Advanced usage

Typically the script should realize if you are using POD structure or not and find its way to components directory.

If you have problems with that, consider:

Forcing POD

To force using POD use --pods argument (alias: -p). Like this:

$ npx ember-unused-components --pods

The script will use the default directory of POD components: app/components. Please let me know if you had to force using POD. I made a simple guessing algorithm that should handle PODs out-of-the-box.

Forcing POD with the custom directory

Your app should be configured to have podModulePrefix property in config/environment.js if you are using POD but if it somehow doesn't work you can specify it through --pods-dir (alias: -pd). Like this:

$ npx ember-unused-components --pods --pods-dir="modules/components-repository"

Configuration

In typical use cases, it should work out of the box and you don't have to configure anything but you can consider the following options. First, you need to create .eucrc.js file in the root directory:

module.exports = {
  whitelist: [
    'app/app-tab-panel' // we will use it again soon
  ],
  ignore: [
    'app/templates/freestyle.hbs' // this is our template with style guides
  ],
  failOnUnused: false // optional, default is false, should we throw errors when we find unused components (useful in CI)
};

Whitelist

You can specify which components should not be treated as unused even if the script couldn't find their usage occurrences. This happens when:

• you know that the component will be used in the future and you don't want to remove it and being reminded of that
• you use some kind of "dynamic name resolution" for your components

---

For the "dynamic name resolution" scenario consider following example. Typical dynamic component look like this:

Template

{{component name car=car}}

JavaScript

name: computed('car.type', function () {
  return `car-card-${this.get('car.type')}`;
});

Result

Which may result in having following components in use:

• car.type = 'suv' => {{car-card-suv car=car}}
• car.type = 'sport' => {{car-card-sport car=car}}
• car.type = 'sedan' => {{car-card-sedan car=car}}

Unfortunately, this static analysis tool doesn't understand it yet and doesn't know that your component car-card-suv has been used anywhere. You can whitelist these components from being marked as unused by referencing to them directly:

module.exports = {
  whitelist: [
    'car-card-suv',
    'car-card-sport',
    'car-card-sedan'
  ]
};

or by using wildcard:

module.exports = {
  whitelist: ['car-card-*']
};

Ignored files

A component might be used in some files like guidelines template (see ember-freestyle) that in fact does not indicate that it is in use. The best practice is to ignore that file:

module.exports = {
  ignore: [
    'app/templates/freestyle.hbs' // this is our template with style guides
  ]
};

Fail on unused

You might want to throw errors when unused components are found. This is especially useful when running in CI. This behavior is turned off by default.

Turn this behavior on in 2 ways:

Setting the failOnUnused property of your .eucrc.js file to true.

module.exports = {
  failOnUnused: true
};

// In practice, it might look something like this:

module.exports = {
  failOnUnused: process.env.CI // many CI services like Travis-ci and Circle-ci inject a CI env variable by default.
};

Passing the --fail-on-unused flag to the cli:

./node_modules/.bin/ember-unused-components --fail-on-unused

The .eucrc.js configuration file takes precedence over the cli argument.

Removing components

Auto removing components might be useful but it's not yet supported. Please consider that simple removal of:

• template.hbs or templates/component-name.hbs
• component.js or components/component-name.js
• style.css or styles/components/style.css

might not remove everything you would like. Examples:

• global CSS classes that are no longer used
• 3rd party JS libraries used only in that component
• translation keys that are no longer needed
• assets (images) that are no longer used
• local overwrites/adjustments for that component made by parent's CSS

So you'll still have some dead code because of unused components.

I encourage you to remove components from the list manually.

Best Practices

Once you delete unused components run the script once again :) You might find that now some other components are no longer used. This happens when the component is used in the unused component.

Example:

{{!-- users-list component --}}
{{#each users as |user|}}
  {{user-card user=user}}
{{/each}}

So user-card is being used but in unused component users-list. Once you will delete users-list component then user-card will not be longer used.

Contributing

If you feel like you need some functionality please raise an issue or event better Contribute!

Testing

It's very important to prepare test cases for fixes and new features.

We have a directory test-apps with applications that have different configs and different Ember versions which support or does not support certain "features" like angle brackets components or module unification project structure.

Running tests

• yarn run test

Linting

• yarn run lint

Debugging

• npx ember-unused-components --debug

License

This project is licensed under the MIT License.