Angular Cheat Sheet

Creating Components

import { Component } from '@angular/core'
@Component({
 selector: 'courses',
 template: '<h2>Courses</h2>'
})
export class Component { }

Then, register them in AppModule (or the module the belong to):

@NgModule({
 declarations: [CoursesComponent]
})
export class AppModule { … }

Using Components

import { CoursesComponent } from './courses.component'
@Component({
 template: '<courses></courses>'
})

Templates
Interpolation syntax:
{{ title }}

Displaying lists:
<ul>
 <li *ngFor=“let course of courses”>
 {{ course }}
 </li>
</ul>

Services

import { Injectable } from '@angular/core';
@Injectable()
export class CourseService {
}

Dependency Injection

Register a service as a provider in AppModule (or the module it belongs to):

@NgModule({
 providers: [CourseService]
})
export class AppModule { … }

Then, inject it into the constructor of the components that need it:

export class CourseComponent {
 constructor(courseService: CourseService) {}
}

Directives
Basic structure
import { Directive } from '@angular/core'

@Directive({
 selector: '[autoGrow]',
 host: {
 '(focus)': 'onFocus()',
 '(blur)': 'onBlur()'
 }
})
export class AutoGrowDirective {
 onFocus() { … }
 onBlur() { … }
}

To access and modify DOM elements

import { ElementRef, Renderer } from '@angular/core'

export class AutoGrowDirective {
 constructor(
 private el: ElementRef,
 private renderer: Renderer) {
 }
 onFocus(){
 this.renderer.setElementStyle(this.el.nativeElement,
 'width', '200');
 }
}

Registration

Once you implement a directive, you should register it in AppModule (or the module it belong to):

@NgModule({
 declarations: [AutoGrowDirective]
})
export class AppModule { }

Angular Bindings

Interpolation
<h1>{{ title }}</h1>

Property binding
<img [src]="imageUrl" />
<img bind-src="imageUrl" />

Class binding
<li [class.active]="isActive" />

Style binding
<button [style.backgroundColor]="isActive ? 'blue' : 'gray'">

Event binding
<button (click)="onClick($event)">
<button on-click="onClick($event)">

Two-way binding
<input type="text" [(ngModel)]="firstName">
<input type="text" bindon-ngModel="firstName">

Input Properties
Using @Input annotation
import { Input } from ‘@angular/core’;
@Component(…)
export class FavoriteComponent {
 @Input(‘is-favorite’) isFavorite = false;
}

Using component metadata
@Component({
 inputs: [‘isFavorite:is-favorite’]
})
export class FavoriteComponent {
 isFavorite = false;
}

In the host component
<favorite [is-favorite]=“post.isFavorite”></favorite>


Output Properties
Using @Output annotation
import { Output } from ‘@angular/core’;
@Component(…)
export class FavoriteComponent {
 @Output(‘favorite-change’) change = new EventEmitter();

 onClick() {
 this.change.emit({ newValue: this.isFavorite });
 }
}


Using component metadata
@Component({
 outputs: [‘change:favoriteChange’]
})
export class FavoriteComponent {
 change = new EventEmitter();

 onClick() {
 this.change.emit({ newValue: this.isFavorite });
 }
}


In the host component
<favorite (favoriteChange)=“onChange()”></favorite>


Templates
@Component({
 template: ‘…’, // or
 templateUrl: ‘app/template.template.html’
})


Styles
@Component({
 styles: [‘…’],
 styleUrls: [‘…’, ‘…’];
})