Taxallus (alias)

Ifodalarni takrorlamaslik uchun as dan foydalanib, haqiqiy qiymatdan mahalliy taxallus yarating.

*ngIf da as taxallus nima?

• Shartning haqiqiy qiymati uchun mahalliy taxallus yarating.
• Misol: *ngIf="user as u" keyin u ichida u dan foydalaning.
• Ifodalarni takrorlamaslik orqali shablonlarni tozalaydi.

as bilan taxallusdan qachon foydalanish kerak

• Xuddi shu iboraga bir necha marta murojaat qilinganda.
• Qiymatga muhtoj bo‘lgan else shablonidan foydalanganda.
• O‘qishni yaxshilash va takrorlashni kamaytirish uchun.

import { bootstrapApplication } from '@angular/platform-browser';
import { Component } from '@angular/core';
import { CommonModule } from '@angular/common';

@Component({
  selector: 'app-root',
  standalone: true,
  imports: [CommonModule],
  template: `
    <button (click)="toggle()">Toggle user</button>
    <p *ngIf="user as u; else empty">Hello {{ u.name }}!</p>
    <ng-template #empty>No user</ng-template>
  `
})
export class App {
  user: { name: string } | null = { name: 'Ada' };
  toggle() { this.user = this.user ? null : { name: 'Ada' }; }
}

bootstrapApplication(App);

<app-root></app-root>

Misol tushuntirildi

• *ngIf="user as u": Agar foydalanuvchi to‘g‘ri bo‘lsa, foydalanuvchi qiymatiga ega bo‘lgan u mahalliy taxallusni yarating.
• Taxallusdan foydalanish: Blok ichida takroriy user.name o‘rniga u.name dan foydalaning.
• else empty : user noto‘g‘ri bo‘lsa, #empty havola qilingan shablonni ko‘rsating.
• toggle() : Tugma ikkala yo‘lni ko‘rsatish uchun null va obyekt o‘rtasida user ni almashtiradi.