feat(challenge36): add solution on trackby

apps/performance/ngfor-optimize/.eslintrc.json

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+{
+  "extends": ["../../../.eslintrc.json"],
+  "ignorePatterns": ["!**/*"],
+  "overrides": [
+    {
+      "files": ["*.ts"],
+      "rules": {
+        "@angular-eslint/directive-selector": [
+          "error",
+          {
+            "type": "attribute",
+            "prefix": "app",
+            "style": "camelCase"
+          }
+        ],
+        "@angular-eslint/component-selector": [
+          "error",
+          {
+            "type": "element",
+            "prefix": "app",
+            "style": "kebab-case"
+          }
+        ]
+      },
+      "extends": [
+        "plugin:@nx/angular",
+        "plugin:@angular-eslint/template/process-inline-templates"
+      ]
+    },
+    {
+      "files": ["*.html"],
+      "extends": ["plugin:@nx/angular-template"],
+      "rules": {}
+    }
+  ]
+}

apps/performance/ngfor-optimize/README.md

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+# NgFor Optimization
+
+> Author: Thomas Laforge
+
+### Run Application
+
+```bash
+npx nx serve performance-ngfor-optimize
+```
+
+### Documentation and Instruction
+
+Challenge documentation is [here](https://angular-challenges.vercel.app/challenges/angular-performance/36-ngfor-optimize/).

apps/performance/ngfor-optimize/jest.config.ts

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+/* eslint-disable */
+export default {
+  displayName: 'performance-ngfor-optimize',
+  preset: '../../../jest.preset.js',
+  setupFilesAfterEnv: ['<rootDir>/src/test-setup.ts'],
+  coverageDirectory: '../../../coverage/apps/performance/ngfor-optimize',
+  transform: {
+    '^.+\\.(ts|mjs|js|html)$': [
+      'jest-preset-angular',
+      {
+        tsconfig: '<rootDir>/tsconfig.spec.json',
+        stringifyContentPathRegex: '\\.(html|svg)$',
+      },
+    ],
+  },
+  transformIgnorePatterns: ['node_modules/(?!.*\\.mjs$)'],
+  snapshotSerializers: [
+    'jest-preset-angular/build/serializers/no-ng-attributes',
+    'jest-preset-angular/build/serializers/ng-snapshot',
+    'jest-preset-angular/build/serializers/html-comment',
+  ],
+};

apps/performance/ngfor-optimize/project.json

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+{
+  "name": "performance-ngfor-optimize",
+  "$schema": "../../../node_modules/nx/schemas/project-schema.json",
+  "projectType": "application",
+  "prefix": "app",
+  "sourceRoot": "apps/performance/ngfor-optimize/src",
+  "tags": [],
+  "targets": {
+    "build": {
+      "executor": "@angular-devkit/build-angular:browser",
+      "outputs": ["{options.outputPath}"],
+      "options": {
+        "outputPath": "dist/apps/performance/ngfor-optimize",
+        "index": "apps/performance/ngfor-optimize/src/index.html",
+        "main": "apps/performance/ngfor-optimize/src/main.ts",
+        "polyfills": ["zone.js"],
+        "tsConfig": "apps/performance/ngfor-optimize/tsconfig.app.json",
+        "assets": [
+          "apps/performance/ngfor-optimize/src/favicon.ico",
+          "apps/performance/ngfor-optimize/src/assets"
+        ],
+        "styles": [
+          "apps/performance/ngfor-optimize/src/styles.scss",
+          "./node_modules/@angular/material/prebuilt-themes/indigo-pink.css"
+        ],
+        "scripts": [],
+        "allowedCommonJsDependencies": ["seedrandom"]
+      },
+      "configurations": {
+        "production": {
+          "budgets": [
+            {
+              "type": "initial",
+              "maximumWarning": "500kb",
+              "maximumError": "1mb"
+            },
+            {
+              "type": "anyComponentStyle",
+              "maximumWarning": "2kb",
+              "maximumError": "4kb"
+            }
+          ],
+          "outputHashing": "all"
+        },
+        "development": {
+          "buildOptimizer": false,
+          "optimization": false,
+          "vendorChunk": true,
+          "extractLicenses": false,
+          "sourceMap": true,
+          "namedChunks": true
+        }
+      },
+      "defaultConfiguration": "production"
+    },
+    "serve": {
+      "executor": "@angular-devkit/build-angular:dev-server",
+      "configurations": {
+        "production": {
+          "browserTarget": "performance-ngfor-optimize:build:production"
+        },
+        "development": {
+          "browserTarget": "performance-ngfor-optimize:build:development"
+        }
+      },
+      "defaultConfiguration": "development"
+    },
+    "extract-i18n": {
+      "executor": "@angular-devkit/build-angular:extract-i18n",
+      "options": {
+        "browserTarget": "performance-ngfor-optimize:build"
+      }
+    },
+    "lint": {
+      "executor": "@nx/linter:eslint",
+      "outputs": ["{options.outputFile}"],
+      "options": {
+        "lintFilePatterns": [
+          "apps/performance/ngfor-optimize/**/*.ts",
+          "apps/performance/ngfor-optimize/**/*.html"
+        ]
+      }
+    },
+    "test": {
+      "executor": "@nx/jest:jest",
+      "outputs": ["{workspaceRoot}/coverage/{projectRoot}"],
+      "options": {
+        "jestConfig": "apps/performance/ngfor-optimize/jest.config.ts",
+        "passWithNoTests": true
+      },
+      "configurations": {
+        "ci": {
+          "ci": true,
+          "codeCoverage": true
+        }
+      }
+    }
+  }
+}

apps/performance/ngfor-optimize/src/app/app.component.ts

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+import { Component, OnInit, inject } from '@angular/core';
+import { FormsModule } from '@angular/forms';
+import { MatFormFieldModule } from '@angular/material/form-field';
+import { MatInputModule } from '@angular/material/input';
+import { PersonService } from './list.service';
+import { PersonListComponent } from './person-list.component';
+
+@Component({
+  standalone: true,
+  imports: [
+    PersonListComponent,
+    FormsModule,
+    MatFormFieldModule,
+    MatInputModule,
+  ],
+  providers: [PersonService],
+  selector: 'app-root',
+  template: `
+    <h1 class="font-semibold text-center text-3xl" title="Title">
+      List of Persons
+    </h1>
+
+    <mat-form-field class="w-3/4">
+      <input
+        placeholder="Add one member to the list"
+        matInput
+        type="text"
+        [(ngModel)]="label"
+        (keydown)="handleKey($event)" />
+    </mat-form-field>
+
+    <app-person-list
+      class="max-w-2xl w-3/4"
+      [persons]="persons()"
+      (delete)="personService.deletePerson($event)"
+      (update)="personService.updatePerson($event)" />
+  `,
+  host: {
+    class: 'flex items-center flex-col gap-5',
+  },
+})
+export class AppComponent implements OnInit {
+  readonly personService = inject(PersonService);
+  readonly persons = this.personService.persons;
+
+  label = '';
+
+  ngOnInit(): void {
+    this.personService.loadPersons();
+  }
+
+  handleKey(event: any) {
+    if (event.keyCode === 13) {
+      this.personService.addPerson(this.label);
+      this.label = '';
+    }
+  }
+}

apps/performance/ngfor-optimize/src/app/app.config.ts

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+import { ApplicationConfig } from '@angular/core';
+import { provideAnimations } from '@angular/platform-browser/animations';
+
+export const appConfig: ApplicationConfig = {
+  providers: [provideAnimations()],
+};

apps/performance/ngfor-optimize/src/app/generateList.ts

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+import { randEmail, randFirstName } from '@ngneat/falso';
+import { Person } from './person.model';
+
+export function generateList() {
+  const arr: Person[] = [];
+
+  for (let i = 0; i < 50; i++) {
+    arr.push({
+      email: randEmail(),
+      name: randFirstName(),
+    });
+  }
+
+  return arr;
+}

apps/performance/ngfor-optimize/src/app/list.service.ts

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+import { Injectable, inject, signal } from '@angular/core';
+import { randEmail, randFirstName } from '@ngneat/falso';
+import { generateList } from './generateList';
+import { Person } from './person.model';
+
+@Injectable()
+export class PersonService {
+  private readonly fakeBackend = inject(FakeBackendService);
+  readonly persons = signal<Person[]>([]);
+
+  loadPersons() {
+    this.persons.set(generateList());
+  }
+
+  deletePerson(email: string) {
+    this.persons.set(
+      this.fakeBackend
+        .returnNewList(this.persons())
+        .filter((p) => p.email !== email)
+    );
+  }
+
+  updatePerson(email: string) {
+    this.persons.set(
+      this.fakeBackend
+        .returnNewList(this.persons())
+        .map((p) => (p.email === email ? { email, name: randFirstName() } : p))
+    );
+  }
+
+  addPerson(name: string) {
+    this.persons.set([
+      { email: randEmail(), name },
+      ...this.fakeBackend.returnNewList(this.persons()),
+    ]);
+  }
+}
+
+@Injectable({ providedIn: 'root' })
+export class FakeBackendService {
+  returnNewList = (input: Person[]): Person[] => [
+    ...input.map((i) => ({ ...i })),
+  ];
+}

apps/performance/ngfor-optimize/src/app/person-list.component.ts

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+import { Component, EventEmitter, Input, Output } from '@angular/core';
+
+import { CommonModule } from '@angular/common';
+import { Person } from './person.model';
+
+@Component({
+  selector: 'app-person-list',
+  standalone: true,
+  imports: [CommonModule],
+  template: `
+    <div
+      *ngFor="let person of persons"
+      class="flex justify-between items-center border-b">
+      <h3>{{ person.name }}</h3>
+      <div class="flex gap-10 py-1">
+        <button
+          class="border rounded-md p-2 bg-blue-500 text-white"
+          (click)="update.emit(person.email)">
+          UPDATE
+        </button>
+        <button
+          class="border rounded-md p-2 bg-red-500 text-white"
+          (click)="delete.emit(person.email)">
+          DELETE
+        </button>
+      </div>
+    </div>
+  `,
+  host: {
+    class: 'w-full flex flex-col',
+  },
+})
+export class PersonListComponent {
+  @Input() persons: Person[] = [];
+  @Output() delete = new EventEmitter<string>();
+  @Output() update = new EventEmitter<string>();
+}

apps/performance/ngfor-optimize/src/app/person.model.ts

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+export interface Person {
+  email: string;
+  name: string;
+}

apps/performance/ngfor-optimize/src/index.html

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+<!DOCTYPE html>
+<html lang="en">
+  <head>
+    <meta charset="utf-8" />
+    <title>performance-ngfor-optimize</title>
+    <base href="/" />
+    <meta name="viewport" content="width=device-width, initial-scale=1" />
+    <link rel="icon" type="image/x-icon" href="favicon.ico" />
+  </head>
+  <body>
+    <app-root></app-root>
+  </body>
+</html>

apps/performance/ngfor-optimize/src/main.ts

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+import { bootstrapApplication } from '@angular/platform-browser';
+import { appConfig } from './app/app.config';
+import { AppComponent } from './app/app.component';
+
+bootstrapApplication(AppComponent, appConfig).catch((err) =>
+  console.error(err)
+);

apps/performance/ngfor-optimize/src/styles.scss

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+@tailwind base;
+@tailwind components;
+@tailwind utilities;
+
+/* You can add global styles to this file, and also import other style files */

apps/performance/ngfor-optimize/src/test-setup.ts

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+import '@testing-library/jest-dom';
+import 'jest-preset-angular/setup-jest';

apps/performance/ngfor-optimize/tailwind.config.js

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+const { createGlobPatternsForDependencies } = require('@nx/angular/tailwind');
+const { join } = require('path');
+
+/** @type {import('tailwindcss').Config} */
+module.exports = {
+  content: [
+    join(__dirname, 'src/**/!(*.stories|*.spec).{ts,html}'),
+    ...createGlobPatternsForDependencies(__dirname),
+  ],
+  theme: {
+    extend: {},
+  },
+  plugins: [],
+};

apps/performance/ngfor-optimize/tsconfig.app.json

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+{
+  "extends": "./tsconfig.json",
+  "compilerOptions": {
+    "outDir": "../../../dist/out-tsc",
+    "types": []
+  },
+  "files": ["src/main.ts"],
+  "include": ["src/**/*.d.ts"],
+  "exclude": ["jest.config.ts", "src/**/*.test.ts", "src/**/*.spec.ts"]
+}

apps/performance/ngfor-optimize/tsconfig.editor.json

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+{
+  "extends": "./tsconfig.json",
+  "include": ["src/**/*.ts"],
+  "compilerOptions": {
+    "types": ["jest", "node"]
+  }
+}

apps/performance/ngfor-optimize/tsconfig.json

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+{
+  "compilerOptions": {
+    "target": "es2022",
+    "useDefineForClassFields": false,
+    "forceConsistentCasingInFileNames": true,
+    "strict": true,
+    "noImplicitOverride": true,
+    "noPropertyAccessFromIndexSignature": true,
+    "noImplicitReturns": true,
+    "noFallthroughCasesInSwitch": true
+  },
+  "files": [],
+  "include": [],
+  "references": [
+    {
+      "path": "./tsconfig.app.json"
+    },
+    {
+      "path": "./tsconfig.spec.json"
+    },
+    {
+      "path": "./tsconfig.editor.json"
+    }
+  ],
+  "extends": "../../../tsconfig.base.json",
+  "angularCompilerOptions": {
+    "enableI18nLegacyMessageIdFormat": false,
+    "strictInjectionParameters": true,
+    "strictInputAccessModifiers": true,
+    "strictTemplates": true
+  }
+}

apps/performance/ngfor-optimize/tsconfig.spec.json

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+{
+  "extends": "./tsconfig.json",
+  "compilerOptions": {
+    "outDir": "../../dist/out-tsc",
+    "module": "commonjs",
+    "types": ["jest", "node", "@testing-library/jest-dom"]
+  },
+  "files": ["src/test-setup.ts"],
+  "include": [
+    "jest.config.ts",
+    "src/**/*.test.ts",
+    "src/**/*.spec.ts",
+    "src/**/*.d.ts"
+  ]
+}