Decorators for Angular (ngx-decorators)

Manage your Angular components like a boss.

NOTE! Decorators for Angular is not compatible with Angular AOT compilation.

Installation

Install using NPM CLI

npm install --save ngx-decorators

or using Yarn CLI

yarn add ngx-decorators

Use cases

Custom component decorator

Do you find yourself copying and pasting the same decorator configuration options for your components?

Create a custom component decorator and use it as a drop-in replacement for Component from @angular/core. You only need to change the import statement.

Customize defaults

The Angular component decorator defaults to emulated view encapsulation and the default change detection strategy.

Create a custom component decorator with no view encapsulation, native view encapsulation (shadow DOM) and the OnPush change detection strategy. Set defaults or enforce your choices.

Build your own component options combinators

We have included helpers for managing change detection and view encapsulation as well as adding a common class to the host component.

Create your own component options combinators to manage white space preservation in component templates, add host element attributes, host styles or any other current or future component option.

Usage

Angular Material uses TSLint rules to enforce common component decorator options. Let us create a custom component decorator to enforce the common options.

import {
  ChangeDetectionStrategy,
  Component as ComponentOptions,
  ViewEncapsulation,
} from '@angular/core';
import {
  ComponentOptionsCombinator,
  createComponentDecorator,
  CustomComponentDecorator,
  forceChangeDetection,
  forceViewEncapsulation,
} from 'ngx-decorators';

const detectChangesOnPush: ComponentOptionsCombinator =
  forceChangeDetection(ChangeDetectionStrategy.OnPush);
const noViewEncapsulation: ComponentOptionsCombinator =
  forceViewEncapsulation(ViewEncapsulation.None);
const alwaysMinifyTemplate: ComponentOptionsCombinator =
  (options: ComponentOptions): ComponentOptions => ({
    ...options,
    preserveWhitespaces: false,
  });

export const Component: CustomComponentDecorator = createComponentDecorator([
  detectChangesOnPush,
  noViewEncapsulation,
  alwaysMinifyTemplate,
]);

You can omit the types if you find it less distracting:

// src/app/decorators/component.decorator.ts
import {
  ChangeDetectionStrategy,
  Component as ComponentOptions,
  ViewEncapsulation,
} from '@angular/core';
import {
  createComponentDecorator,
  forceChangeDetection,
  forceViewEncapsulation,
} from 'ngx-decorators';

const detectChangesOnPush =
  forceChangeDetection(ChangeDetectionStrategy.OnPush);
const noViewEncapsulation =
  forceViewEncapsulation(ViewEncapsulation.None);
const alwaysMinifyTemplate = options => ({
    ...options,
    preserveWhitespaces: false,
  });

export const Component = createComponentDecorator([
  detectChangesOnPush,
  noViewEncapsulation,
  alwaysMinifyTemplate,
]);

Now we are ready to use it in our project.

Before we had

(sample from Angular Material version 5)

import { Component } from '@angular/core';

@Component({
  moduleId: module.id,
  selector: 'mat-card',
  exportAs: 'matCard',
  templateUrl: 'card.html',
  styleUrls: ['card.css'],
  encapsulation: ViewEncapsulation.None,
  preserveWhitespaces: false,
  changeDetection: ChangeDetectionStrategy.OnPush,
  host: {'class': 'mat-card'}
})
export class MatCard {}

Now we are left with

import { Component } from '../decorators/component.decorator';

@Component({
  moduleId: module.id,
  selector: 'mat-card',
  exportAs: 'matCard',
  templateUrl: 'card.html',
  styleUrls: ['card.css'],
  host: {'class': 'mat-card'}
})
export class MatCard {}

Even if we by accident add the default change detection strategy or emulated view encapsulation, our custom component decorator takes care of it for us. This is of course entirely customizable.

Look at the example app in this repository to see our various helpers in-use.

Supported Angular versions

Decorators for Angular has been tested with Angular versions 2 through 6. It is unlikely that it will stop working until Angular's component decorator or the public API of @angular/core gets breaking changes.

Caveats

Angular AOT compilation

Angular AOT compilation does not support arrow functions or function expressions. While the arrow functions can easily be converted to function declarations, this library does not contribute anything without its combinator creators that are using function expressions.

Node.js

Do not use a custom component decorator for your root component, i.e. AppComponent unless you are using Node.js version 9 or newer.

Attributions

Thank you Mahmoud Abduljawad for your support, ideation and testing.