Angular unused css detection

TLDR: Simple example can be found here: https://github.com/ivanblazevic/ngx-unused-css/tree/master/examples/simpleAngularApp

How does it works:

• it finds all .html files inside the project and then pairs it with their styling files; e.g. app.component.html > app.component.scss
• if pair is matched then it will compare unused css using PurgeCSS library
• SCSS will be automatically compiled before the matching phase
• some system selectors like :host or ::ng-deep will be ignored
• with configuration it is possible to extend global selectors to ignore
• configure ignore per file in case CSS class is applied dynamically; ENUMS or based on backend model

Installation

Global: npm install -g ngx-unused-css

or

Local: npm install ngx-unused-css --save-dev

Add configuration file in the root of the project

.ngx-unused-css.json

Usage

Run in CLI if installed globally like: ngx-unused-css

or add it to package.json > scripts: "unused-css": "ngx-unused-css" and run in CLI: npm run unused-css

Optionally, override config path with CLI param: ngx-unused-css --config=otherConfig

Options

path

• Type: String
• Default: null

Path to a project, for Angular it is usually src/app

globalStyles

• Type: String
• Default: null

Path to global styles, usally it is src/styles.scss

importer

Custom importer handler, more details here: https://github.com/sass/node-sass#importer--v200---experimental

includePaths

Refer to original documentation: https://github.com/sass/node-sass#includepaths

ignore

• Type: Array<String | Object>
• Default: null

Selectors to ignore, they can be defined globally (as an string) or specific per file (as an object). This comes useful when class is applied based on the value from the backend, e.g.

[ngClass]="model.status.toLowerCase()" class is dervied from the backend so there is no possibility to do the analysis.

Special: global as a string, or Object as a file specific

Object

file

• Type: String
• Default: null

Path to css file, relative to projectPath

selectors

• Type: Array<String>
• Default: null

Array of selectors inside the file

all

• Type: Boolean
• Default: false

If set as true it will ignore selectors property (if defined) and will ignore whole file

Example: Ignore .dynamic-class in app.component.scss:

{
  file: "app.component.scss",
  selectors: [".dynamic-class"]
}

Example: Ignore whole app.component.scss:

{
  file: "app.component.scss",
  all: true
}

Example: Ignore ng-star globally and .test-2 inside test.component.scss file:

{
    "path": "src/app",
    "ignore": [
        "ng-star",
        {
            "file": "test.component.scss",
            "selectors": [".test-2"]
        }
    ]
}

ngClass handling

If ngClass is found on the element, same element will be duplicated with all possible combination of the classes on the same level and template will be then compared with css definition to match if all possible combinations are used

Example:

<div class="test">
     <div class="test" [ngClass]="{ class1: var1, class2: var2 }"></div>
</div>

To compare against CSS it will recompile html with all possible cases:

<div class="test">
     <div class="test" [ngClass]="{ class1: var1, class2: var2 }"></div>
     <div class="test class1"></div>
     <div class="test class2"></div>
     <div class="test class1 class2"></div>
</div>

NOTE: This library will not detect nested ngClasses

Special cases

Template files that are not matching their styling counter part will be ignored