Displaying a list in Angular 2/4 without keeping track of any modifications

Question

Displaying a list in Angular 2/4 without keeping track of any modifications

Is there a way to display a list of strings without tracking changes? (I'm experiencing performance issues).

Fetching a list of languages from a REST API and then dynamically generating dropdowns for each language using *ngFor is causing the app to slow down when there are 10+ dropdowns (10 dropdowns * 200 languages = 2000 items to track).

The ideal solution would be to disable change tracking on the languages list since it will never be altered, but this process is not documented.

Code

Controller

langs: string[] = ['English', 'German', 'Spanish', ...];

View

<select ...>
    <option *ngFor="lang of langs">{{lang}}</option>
</select>

javascript performance angular typescript ngfor

Answer 1

Answer №1

To assist Angular in monitoring the addition or removal of items, we can implement a custom trackBy function. This function is responsible for returning a unique identifier for each item based on its index and current value.

With this custom tracking mechanism in place, Angular can efficiently detect which items have been added or removed when the collection changes. It then only creates or destroys the necessary elements accordingly. For more information, refer to the documentation available at: https://angular.io/api/common/NgForOf

Answer 2

To assist Angular in monitoring the addition or removal of items, we can implement a custom trackBy function. This function is responsible for returning a unique identifier for each item based on its index and current value.

With this custom tracking mechanism in place, Angular can efficiently detect which items have been added or removed when the collection changes. It then only creates or destroys the necessary elements accordingly. For more information, refer to the documentation available at: https://angular.io/api/common/NgForOf

Displaying a list in Angular 2/4 without keeping track of any modifications

Answer №1

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