5 Points about filter in Angular

If you are working with data in an Angular application, you may need to filter the data based on certain criteria. Angular provides a powerful filter feature that allows you to easily accomplish this task. In this article, we will explore 5 important points about using filters in Angular.

1. Basic Syntax

To use the filter feature in Angular, you can simply add the “filter” pipe to the end of your ngFor directive. For example:


<ul>
<li *ngFor="let item of items | filter:searchText">{{ item.name }}</li>
</ul>


2. Default Filter

By default, the filter feature in Angular performs a simple case-insensitive substring match. This means that if the search text is found anywhere within the item’s property, it will be included in the filtered result.

3. Custom Filter

If you need more control over the filtering process, you can create a custom filter function in your component. This function can perform more complex matching logic and return the filtered result. For example:


customFilter(items: any[], searchText: string): any[] {
// Custom filtering logic here
}


4. Async Pipe

If you are working with asynchronous data, you can use the async pipe in conjunction with the filter pipe to handle the data stream. This allows the filter to automatically update as new data is received.

5. Performance Considerations

When working with large datasets, it’s important to consider the performance implications of using filters. Applying filters to large arrays can be computationally expensive, so it’s important to optimize your filtering logic and consider using memoization techniques to improve performance.