Executing a function in the view/template with Angular 2+

Question

Executing a function in the view/template with Angular 2+

Whenever a function is called in the view of an Angular component, it seems to be executed repeatedly. A typical example of this scenario can be seen below:

nightclub.component.ts

import { Component } from '@angular/core';

@Component({
  selector: 'app-nightclub',
  templateUrl: './nightclub.component.html',
  styleUrls: ['./nightclub.component.css']
})
export class NightclubComponent {
  doStuff(): number {
    return 1;
  }
}

nightclub.component.html

{{doStuff()}}

As observed, the doStuff() method is constantly being invoked.

Question:

Is it recommended to have functions called repeatedly in this manner? If so, under what circumstances could this practice prove to be advantageous?

javascript angular typescript angular-components

Answer 1

Answer №1

It is recommended to avoid using a function inside the template, as it will be called every change detection cycle and can result in a performance impact.

The way you implement the function or data displayed on the template greatly depends on your specific use case.

For example:

If you are parsing text, using a pipe would be an efficient choice since it can be memoized.

If changes to the data may occur outside of the component where Inputs and Outputs cannot be utilized, then using an Observable is a good solution.

Answer 2

It is recommended to avoid using a function inside the template, as it will be called every change detection cycle and can result in a performance impact.

The way you implement the function or data displayed on the template greatly depends on your specific use case.

For example:

If you are parsing text, using a pipe would be an efficient choice since it can be memoized.

If changes to the data may occur outside of the component where Inputs and Outputs cannot be utilized, then using an Observable is a good solution.

Answer 3

Answer №2

Aside from the responses and comments, I would like to offer some suggestions to enhance your code optimization. To begin with, I recommend watching this informative video (~40 minutes) from ng-conf on optimizing Angular applications by Minko Gechev.

The key takeaway is to implement the OnPush change detection strategy in your components, utilize Pure Pipes for methods like the one in your example, and consider memoizing functions.

If you have the OnPush Strategy enabled in your Component but changes are coming from outside of Angular's control, you can also inject ChangeDetectorRef into your component and manually invoke markForCheck() (for more information, refer to the official documentation).

Answer 4

Aside from the responses and comments, I would like to offer some suggestions to enhance your code optimization. To begin with, I recommend watching this informative video (~40 minutes) from ng-conf on optimizing Angular applications by Minko Gechev.

The key takeaway is to implement the OnPush change detection strategy in your components, utilize Pure Pipes for methods like the one in your example, and consider memoizing functions.

If you have the OnPush Strategy enabled in your Component but changes are coming from outside of Angular's control, you can also inject ChangeDetectorRef into your component and manually invoke markForCheck() (for more information, refer to the official documentation).

Executing a function in the view/template with Angular 2+

Question:

Answer №1

Answer №2

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