Angular is a JavaScript-based open-source framework that allows developers to create single-page web applications. It is one of the most popular frameworks among developers, with over 1.5 million active sites.Ā The Angular framework has been optimized for performance and speed, but it can be difficult to ensure that your app performs well on a variety of platforms and devices. Thatās when the need for Angular performance optimization arises.
The Angular Performance Optimization techniques provide a quick and easy way to improve the performance of your Angular applications. These techniques improve various parameters viz user experiences, such as scrolling speed, loading times, and network latency. And it is not limited to a particular device, browser and operating system.
Angular App Performance Optimization Techniques
Angular performance optimization is a very important part of any web development project. The reason for this is that it affects the user experience and so can be seen as a key factor in the success of the project.
For example, if your application is running too slowly, you can instantly increase the speed of your application by optimising the build process. Optimising a web application is also very important in order to get it to perform at the highest level possible and stay competitive in the market.
Here are some of the methods you can use for optimising your Angular applications:
Ahead Of Time Compilation
Ahead of time compilation is a process that compiles a projectās Javascript, CSS, and HTML code into one build. This process speeds up the development by reducing the time spent on compiling and minifying.
In order to have a successful ahead-of-time compilation, the Javascript, CSS, and HTML files should be compiled together at the same time. This can be done by setting up a build system with grunt or gulp and configuring it to run when files in the project change.
Detect Changes Manually
In some cases, you have to detach change detection for some components. It would be detrimental to an app if a component instantiated 10ās of time and caused rerender of every component. In such cases, it is recommended to trigger changes manually.
Letās see how to do this for todoItems:
@Component({
selector: āapp-todo-item-list-rowā,
templateUrl: ā./todo-item-list-row.component.htmlā,
styleUrls: [ā./todo-item-list-row.component.scssā],
changeDetection: ChangeDetectionStrategy.OnPush
})
export class TodoItemListRowComponent implements OnInit {private _todoItem : TODOItem;
public get todoItem() : TODOItem {
return this._todoItem;
}
@Input()
public set todoItem(v : TODOItem) {
this._todoItem = v;
this.cdr.detectChanges();
}@Input() public readOnlyTODO: boolean;
@Output() public todoDelete = new EventEmitter();
@Output() public todoEdit = new EventEmitter();
@Output() public todoComplete = new EventEmitter();constructor(private cdr: ChangeDetectorRef) {}
public ngOnInit() {
this.cdr.detach();
}public completeClick() {
const newTodo = {
ā¦this.todoItem,
completed: !this.todoItem.completed
};this.todoComplete.emit(newTodo);
}public deleteClick() {
this.todoDelete.emit(this.todoItem.id);
}public editClick() {
this.todoEdit.emit(this.todoItem);
}
}
Speeding Page Load Time
The page load time is an important aspect from the perspective of SEO as well as user experience. With every millisecond of prolonged page load time, you are likely to make a loss in revenue. A user would not like to wait for a page to load; thus, they hit the ābackā button and increase the bounce rate.
Angular developers can reduce loading to a great extent with caching in Angular PWA and bundling.
Caching The Static Content With Angular PWA
Angular PWA makes use of service workers to cache the static content, which includes images, bundles, JS, CSS, and statically served files, without requesting it from the server as it will already be stored in the browser.
Cache HTTP Calls
In Angular PWA, you can set up caching rules for HTTP calls to deliver a faster user experience in such a way that your app does not get cluttered with dozens of lines of caching code.
Lazy Loading
Performance optimization of Angular apps can be done by applying a lazy loading technique which loads only the required modules and components on demand, thereby reducing initial loading time.
Angular CLI supports a lazy loading technique through the use of the ng-lazy attribute. This attribute is used to cause Angular to load and render only what is needed. This helps to minimise initial overhead while still providing a rich user experience.
Following is the technique to setup lazy loading:
const routes: Routes = [
{
path: ā,
component: BookListComponent
}
];
export const BookListComponent = RouterModule.forChild(routes);
Then add this route to imports:
@NgModule({
imports: [FormsModule, CommonModule, SharedModule, TodoListCompletedRoutes],
declarations: [BookListComponent]
})
export class BookListComponentModule {}
At last, lazy load the component with the help of loadChildren in the root route:
const appRoutes: Routes = [
{
path: rootPath,
component: BookListComponent,
pathMatch: āfullā
},
{
path: BookListComponent,
loadChildren: ā./book-list-component/book.list.component.module#BookListComponentModuleā
}
];export const appRouterModule = RouterModule.forRoot(appRoutes);
Server-side Rendering
Server-side rendering (SSR) is a technique that renders your Angular app on the server and sends it to the client instead of doing all of its processing on the client, which can lead to significant performance improvements in some scenarios. It allows us to provide an instant response time and improve user experience. It also increases security and improves SEO greatly.
To implement SSR, you need to build a renderer service that will take care of processing the DOM events and executing your Angular code. You can use Angular Universalās Renderer Service in this case.
Preloading
Preload is a service that is provided by your web application so that most of the data, such as HTML, CSS and JavaScript files, can be preloaded in the browser to speed up the loading time of the web page. The preloading is done by loading the files into your database and then storing them to be executed later on.
However, if the same web page is accessed again without refreshing or reloading, then it will use the cached version and hence does not require any extra loading time. The problem with caching is that you need to know how often your application needs to refresh for optimal caching.
An angular developer has to implement this strategy in the @angularangular/router module. This enables us to preload resources, such as web pages, audio, video files and modules also.
This is how you can implement pre-loading strategy:
class OurPreloadingStrategy implements PreloadingStrategy {
preload(route: Route, fn: ()=> Observable ) {
// ā¦
}
}
We mention its value for the preloading in the router configuration.
// ā¦
RouterModule.forRoot([
ā¦
], {
preloadingStrategy: OurPreloadingStrategy
})
// ā¦
Over To You
With Angular performance optimization, you can increase the speed and responsiveness of your application. This will improve your user experience and increase your engagement rate. On the other hand, if you want to increase your applicationās scalability, you will have to tackle the performance problem as soon as possible. Hence it is in good faith that you implement performance optimization techniques sooner.
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