Direktif yaiku kelas-kelas sing nambah kapriyatnan utawa ngowahi unsur-unsur ing DOM. Angular nduweni telung jenis: komponen (direktif kanthi template), direktif struktural (ngowahi tata letak DOM), lan direktif atribut (ngowahi penampilan/kapriyatnan).
Kul nambah utawa ngilangi unsur-unsur, lan dirabi awalan :
*<p *ngIf="isLoggedIn">Welcome back!</p> <!-- add/remove based on condition -->
<li *ngFor="let item of items; let i = index"> <!-- repeat an element per item -->
{{ i }}: {{ item.name }}
</li>
<div [ngSwitch]="status">
<p *ngSwitchCase="'active'">Active</p>
<p *ngSwitchDefault>Unknown</p>
</div>
(Angular modern uga nawakake sintaks kontrol aliran sing luwih anyar @if / @for sing ngganti *ngIf/*ngFor.)
Kul ngowahi unsur sing wis ana tanpa nambah/ngilangi:
<div [ngClass]="{ active: isActive, error: hasError }">...</div> <!-- toggle classes -->
<div [ngStyle]="{ color: textColor }">...</div> <!-- dynamic styles -->
<input [(ngModel)]="name" /> <!-- two-way binding -->
import { Directive, ElementRef, HostListener } from "@angular/core";
@Directive({ selector: "[appHighlight]" }) // used as <p appHighlight>
export class HighlightDirective {
constructor(private el: ElementRef) {}
@HostListener("mouseenter") onEnter() {
this.el.nativeElement.style.background = "yellow"; // change the host element
}
@HostListener("mouseleave") onLeave() {
this.el.nativeElement.style.background = "";
}
}
Direktif khusus entuk referensi menyang elemen host-ne lan bisa tumugon marang acara — ing kene, sorotan nalika mouseover. Digunakake minangka <p appHighlight>Text</p>.
<p *ngIf="x">...</p>
<!-- desugars to: -->
<ng-template [ngIf]="x"><p>...</p></ng-template>
* yaiku singkatan sing mbungkus unsur ing <ng-template> — mula direktif struktural bisa nambah/ngilangi unsur-unsur kanthi rampung.
Direktif yaiku cara Angular ngolah DOM kanthi deklaratif.
Direktif struktural (*ngIf/*ngFor/@if/@for) lan atribut (ngClass/ngStyle/ngModel) sing asil nutupi akeh kebutuhan, lan direktif khusus ndadekake sampeyan bisa nyemak kapriyatnan DOM sing bisa dibaleni maneh (sorotan, tooltip, click-outside).
Ngerteni telung kategori — lan menawa komponen yaiku direktif kanthi template — yaiku inti minangka model template Angular.