How to Improve the Performance of Angular Application?

Angular is one of the most used frameworks for application development. It is especially preferred by developers that need to design a quality dynamic app. The framework follows a modular web development approach, which makes it quite a popular option for web app developers. But, do you know you could improve the performance of your Angular app and make it even more efficient? Fortunately, yes! You can create a high-quality dynamic app with Angular and improve your app with some effective tricks.

Let’s check some easy and effective ways to boost the performance of your Angular app.

Minimize Change Detections

Angular Framework runs change detection in the component. This change detection will detect all the changes in your data. Despite being one of the fastest dynamic app development platforms, Angular has to work harder in order to monitor all the changes.

You could minimize the work of this Framework by giving it an indication regarding when to detect the changes in the component. By changing the default change detection feature to ChangeDetectionStrategy.OnPush, you can reduce the workload of the framework. The On-push strategy will tell Angular to detect changes when you run the detection manually or there is a change in Input reference.

By default, components in an Angular application undergo change detection with nearly every user interaction. But, Angular allows you take control of this process. You can indicate to Angular if a component subtree is up to date and exclude it from change detection.

The first way to exclude a component subtree from change detection is by setting the `changeDetection` property to `ChangeDetectionStrategy.OnPush` in the @Component decorator. This tells Angular that the component only needs to be checked if an input has changed, and that all of the inputs can be considered immutable.

At the price of a bit more complexity it is possible to increase the amount of control. For example, by injecting the ChangeDetectorRef service, you can inform Angular that a component should be detached from change detection. You can then manually take control of calling `reattach` or `detectChanges()` yourself, giving you full control of when and where a component subtree is checked.

Minimize DOM Manipulations

If you ever need to change the data in Angular (perhaps, because of the API request), you will face a lot of issues. This is because Angular does not monitor the data in your collection. It doesn’t know which items are added and deleted.

By adding the Trackby functionality, you could request Angular to detect the data that has been added and deleted based on the unique identifier. This way Angular will remove the items that changed.

By default, when iterating over a list of objects, Angular will use object identity to determine if items are added, removed, or rearranged. This works well for most situations. However, with the introduction of immutable practices, changes to the list’s content generates new objects.

In turn, ngFor will generate a new collection of DOM elements to be rendered. If the list is long or complex enough, this will increase the time it takes the browser to render updates. To mitigate this issue, it is possible to use trackBy to indicate how a change to an entry is determined.

Angular Observables Tutorial