feat: solve problem 8 pure pipe

Author: h-ARTS

apps/angular/8-pure-pipe/src/app/app.component.ts

@@ -1,18 +1,15 @@
 import { Component } from '@angular/core';
+import { IndexPipe } from './index.pipe';
 
 @Component({
   selector: 'app-root',
   template: `
-    @for (person of persons; track person) {
-      {{ heavyComputation(person, $index) }}
+    @for (person of persons; track person; let i = $index) {
+      <div>{{ person | indexer: i }}</div>
     }
   `,
+  imports: [IndexPipe],
 })
 export class AppComponent {
   persons = ['toto', 'jack'];
-
-  heavyComputation(name: string, index: number) {
-    // very heavy computation
-    return `${name} - ${index}`;
-  }
 }

apps/angular/8-pure-pipe/src/app/index.pipe.ts

@@ -0,0 +1,11 @@
+import { Pipe, PipeTransform } from '@angular/core';
+
+@Pipe({
+  pure: true,
+  name: 'indexer',
+})
+export class IndexPipe implements PipeTransform {
+  transform(value: string, index: number) {
+    return `${value} - ${index}`;
+  }
+}