Angular, one of the most popular JavaScript frameworks, is widely used for building complex and scalable web applications. However, as applications grow in size and complexity, runtime performance can become a crucial factor. A sluggish application can lead to a poor user experience and negatively impact conversion rates. In this blog post, we will explore techniques and best practices for boosting the runtime performance of Angular applications, ensuring they remain fast and responsive.
Table of Contents
Optimize Change Detection
Change detection is a critical aspect of Angular applications, and optimizing it can significantly improve runtime performance. While there are several techniques to enhance change detection efficiency, we recommend referring to our detailed blog post dedicated to this topic. It covers strategies such as using the OnPush change detection strategy, leveraging immutable data structures, and utilizing the trackBy function for ngFor directive.
Efficient DOM manipulation
Efficient DOM manipulation is a crucial aspect of optimizing the runtime performance of Angular applications. As developers, we strive to deliver fast and responsive web experiences to our users. However, inefficient DOM manipulation can introduce rendering delays, layout recalculations, and unnecessary updates, ultimately degrading the overall performance of the application.
Minimize Direct DOM Manipulation
Angular encourages a declarative approach to DOM manipulation using template directives. However, there may be scenarios where direct DOM manipulation is necessary. To ensure efficiency, follow these guidelines:
- Use Renderer2: When performing DOM manipulations, use Angular’s Renderer2 instead of direct element manipulation. Renderer2 abstracts the underlying DOM implementation and provides a cross-platform solution. It also allows Angular to optimize rendering based on the specific platform requirements. Here’s an example:
import { Component, Renderer2, ElementRef } from '@angular/core';
@Component({
selector: 'app-dom-manipulation',
template: `
<button (click)="changeColor()">Change Color</button>
`,
})
export class DomManipulationComponent {
constructor(private renderer: Renderer2, private elementRef: ElementRef) {}
changeColor(): void {
const buttonElement = this.elementRef.nativeElement.querySelector('button');
this.renderer.setStyle(buttonElement, 'background-color', 'red');
}
}In the above example, instead of directly manipulating the button element’s style, we use the Renderer2’s setStyle() method to modify the background color. By using Renderer2, Angular can optimize the DOM update and ensure compatibility across different platforms.
- Batch DOM Updates: When making multiple changes to the DOM, batch them together using Angular’s zone.run() or setTimeout(). Batching updates minimizes layout recalculations and improves overall performance.
import { Component, Renderer2, ElementRef } from '@angular/core';
@Component({
selector: 'app-batch-dom-updates',
template: `
<button (click)="batchUpdates()">Batch Updates</button>
`,
})
export class BatchUpdatesComponent {
constructor(private renderer: Renderer2, private elementRef: ElementRef) {}
batchUpdates(): void {
const buttonElement = this.elementRef.nativeElement.querySelector('button');
// Batch multiple updates using setTimeout()
setTimeout(() => {
this.renderer.addClass(buttonElement, 'highlight');
this.renderer.setStyle(buttonElement, 'color', 'white');
}, 0);
}
}In this example, we use setTimeout() to batch multiple updates. By deferring the updates to the next tick of the event loop using a minimal timeout (0 milliseconds), the changes are grouped together, reducing layout recalculations and improving performance.
- Avoid Frequent DOM Reads: Reading from the DOM can be expensive. Minimize unnecessary reads by storing frequently accessed elements or properties in variables whenever possible. This reduces the need for frequent DOM queries, improving performance.
Optimize NgFor Loops
NgFor is commonly used to render lists in Angular applications. However, inefficient use of NgFor can impact performance. Consider the following strategies:
- TrackBy Function: When using NgFor, provide a trackBy function to optimize rendering. The trackBy function identifies unique items in the list, allowing Angular to update only the changed items rather than re-rendering the entire list.
import { Component } from '@angular/core';
interface Item {
id: number;
name: string;
}
@Component({
selector: 'app-ng-for-optimization',
template: `
<ul>
<li *ngFor="let item of items; trackBy: trackByFn">{{ item.name }}</li>
</ul>
`,
})
export class NgForOptimizationComponent {
items: Item[] = [
{ id: 1, name: 'Item 1' },
{ id: 2, name: 'Item 2' },
{ id: 3, name: 'Item 3' },
// Add more items...
];
trackByFn(index: number, item: Item): number {
return item.id;
}
}In the above example, the trackByFn() function is defined to return the unique identifier (id) of each item. By specifying this trackBy function in the NgFor loop, Angular can efficiently track and update the items based on their identifiers. This prevents unnecessary re-rendering of the entire list and improves performance when the list changes.
- Limit Iteration Scope: Ensure that NgFor loops iterate over the minimum number of items necessary. Avoid looping through large collections unnecessarily or performing computationally expensive operations within the loop.
import { Component } from '@angular/core';
@Component({
selector: 'app-ng-for-optimization',
template: `
<ul>
<li *ngFor="let item of getFilteredItems()">{{ item.name }}</li>
</ul>
`,
})
export class NgForOptimizationComponent {
items = [
{ id: 1, name: 'Item 1', category: 'A' },
{ id: 2, name: 'Item 2', category: 'B' },
{ id: 3, name: 'Item 3', category: 'A' },
// Add more items...
];
getFilteredItems(): any[] {
return this.items.filter(item => item.category === 'A');
}
}In this example, instead of iterating over the entire items array, we use the getFilteredItems() method to return a filtered subset of items based on a specific criterion (in this case, filtering by the category property). By limiting the iteration scope to only the necessary items, we reduce the number of iterations and improve the performance of the NgFor loop.
Leverage Reactive Programming
Angular provides powerful reactive programming capabilities through RxJS. Leveraging reactive programming techniques can optimize DOM manipulation and improve performance. Consider the following approaches:
- Async Pipe: Use the async pipe in Angular templates to handle asynchronous data streams efficiently. The async pipe automatically manages the subscription and unsubscription, reducing the risk of memory leaks and unnecessary DOM updates.
- Operators and Observables: Utilize RxJS operators to transform and combine data streams effectively. By using operators such as map, filter, and debounceTime, you can minimize unnecessary updates and enhance performance.
Virtual Scrolling
Virtual scrolling is an excellent technique for handling large lists or tables in Angular applications. By rendering only the visible portion of the content, virtual scrolling reduces the number of DOM elements, leading to improved performance. Consider implementing virtual scrolling using libraries like Angular CDK or ngx-virtual-scroller for seamless integration.
Optimised Animations
Animations play a vital role in enhancing user experience and creating engaging Angular applications. However, poorly optimized animations can have a significant impact on the overall performance of your application
Use the Right Animation Trigger
Angular provides various animation triggers such as [@triggerName], [style.property], and [class.name]. It is essential to choose the appropriate trigger based on the animation requirements to minimize unnecessary computations.
Let’s say you have a component that needs to show a slide-in animation when it is first displayed. In this case, you can use the [@triggerName] animation trigger to achieve the desired effect. Here’s an example:
import { Component } from '@angular/core';
import { trigger, transition, style, animate } from '@angular/animations';
@Component({
selector: 'app-slide-in-animation',
template: `
<div [@slideInAnimation]>Hello, Angular!</div>
`,
animations: [
trigger('slideInAnimation', [
transition(':enter', [
style({ transform: 'translateX(-100%)' }),
animate('500ms', style({ transform: 'translateX(0)' }))
])
])
]
})
export class SlideInAnimationComponent { }
In the example above, we define an animation trigger called slideInAnimation. It has a single transition for the :enter state, which is triggered when the component is first displayed. The transition animates the element’s transform property from translateX(-100%) (initial position) to translateX(0) (final position) over a duration of 500 milliseconds.
By using the [@slideInAnimation] syntax in the template, we apply the animation trigger to the <div> element, causing it to slide in from the left when the component is rendered.
In this case, the [@triggerName] trigger is the appropriate choice because we are animating a specific transition, which is the initial appearance of the component. By using the right animation trigger for the desired effect, we can optimize the animation and ensure that unnecessary computations are avoided.
Utilize AnimationBuilder for Complex Animations:
For more complex animations, leverage Angular’s AnimationBuilder to create reusable animation sequences. The AnimationBuilder provides a programmatic way to define animations with fine-grained control over timing, easing, and keyframes. By pre-building the animations and reusing them when necessary, you can reduce runtime computations and improve performance.
import { Component, ElementRef, ViewChild } from '@angular/core';
import { AnimationBuilder, style, animate } from '@angular/animations';
@Component({
selector: 'app-complex-animation',
template: `
<div #animatedElement></div>
<button (click)="startAnimation()">Start Animation</button>
`,
})
export class ComplexAnimationComponent {
@ViewChild('animatedElement', { static: true }) animatedElement: ElementRef;
constructor(private animationBuilder: AnimationBuilder) { }
startAnimation(): void {
const animationFactory = this.animationBuilder.build([
style({ opacity: 0, transform: 'scale(0.5)' }),
animate('500ms', style({ opacity: 1, transform: 'scale(1)' })),
animate('500ms', style({ transform: 'rotate(360deg)' })),
]);
const player = animationFactory.create(this.animatedElement.nativeElement);
player.play();
}
}
In the example above, we have a ComplexAnimationComponent that utilizes the AnimationBuilder to create a complex animation sequence. The component contains a <div> element that we want to animate and a “Start Animation” button. When the button is clicked, the startAnimation() method is called. Inside this method, we define the animation using the AnimationBuilder by specifying a series of styles and keyframes. In this example, we start with an initial state of opacity 0 and a scaled-down size, then animate the element to full opacity and its original size, and finally rotate it 360 degrees.
We create an animation factory using animationBuilder.build() and pass in the array of styles and keyframes. Then, we create an animation player using create() and provide the target element for the animation, which is obtained through ViewChild. Once the animation player is created, we call play() to start the animation.
By utilizing the AnimationBuilder, we have fine-grained control over the animation sequence, including the ability to chain multiple animations together. This allows for the creation of complex and visually appealing animations while maintaining performance by avoiding excessive computations.
Use query() and animateChild() for Hierarchical Animations
When animating nested elements or child components, utilize query() and animateChild() to animate them in a coordinated manner. query() allows you to target specific elements within the animated component, while animateChild() ensures that child components are animated appropriately. This approach optimizes the animation process by executing animations simultaneously and avoids unnecessary computations.
import { Component } from '@angular/core';
import { trigger, transition, style, animate, query, animateChild } from '@angular/animations';
@Component({
selector: 'app-hierarchical-animation',
template: `
<div [@containerAnimation]>
<h2>Parent Component</h2>
<div [@itemAnimation]>Item 1</div>
<div [@itemAnimation]>Item 2</div>
<app-child-component></app-child-component>
</div>
`,
animations: [
trigger('containerAnimation', [
transition(':enter', [
query('@itemAnimation', animateChild()),
])
]),
trigger('itemAnimation', [
transition(':enter', [
style({ opacity: 0, transform: 'translateY(-20px)' }),
animate('500ms', style({ opacity: 1, transform: 'translateY(0)' }))
])
])
]
})
export class HierarchicalAnimationComponent { }
In the above example, we have an HierarchicalAnimationComponent that contains a parent component and child component. The parent component includes a heading and two <div> elements, while the child component is represented by <app-child-component>. We define two animation triggers: containerAnimation and itemAnimation. The containerAnimation is applied to the parent <div>, while the itemAnimation is applied to the <div> elements inside the parent component.
In the containerAnimation trigger, we specify a transition for the :enter state. Inside this transition, we use the query() function to select all elements with the @itemAnimation trigger and apply the animateChild() function. This ensures that all child elements with the itemAnimation trigger are animated when the parent component enters.
By utilizing query() and animateChild(), we can create hierarchical animations that animate both the parent and child elements in a coordinated manner. This ensures a seamless and synchronized animation experience throughout the component hierarchy.
Enable Hardware Acceleration
Leverage hardware acceleration to offload rendering tasks to the GPU and improve animation performance. Use CSS properties like transform and opacity to trigger hardware acceleration, and avoid animating properties like top, left, or width, which can cause layout recalculations. By utilizing hardware acceleration, you can achieve smoother animations with reduced CPU usage.
Limit the Number of Concurrent Animations
To prevent performance degradation, limit the number of simultaneous animations occurring on the screen. Excessive concurrent animations can strain the browser’s resources and lead to reduced frame rates. Consider using animation queues or staggering animations to ensure a controlled and optimized animation experience.
Conclusion
In this blog post, we explored various strategies to boost Angular runtime performance by optimizing change detection, DOM manipulation, and animations. By implementing these techniques, you can significantly improve the responsiveness and efficiency of your Angular applications.
Remember, every optimization counts, and even small improvements can make a significant impact on the overall performance of your Angular application. So, start implementing these techniques today and enjoy faster, more efficient Angular applications!