Angular Pipes

In Angular, pipes are a feature that allows us to transform data directly within our template before displaying it.

Pipes are a simple way to format data for display, perform data manipulation, and apply transformations without modifying the underlying data itself.

Angular provides built-in pipes for common data transformations, and we can also create custom pipes for specific formatting needs.

Benefits of Pipes:

  • Performance Optimization: Pipes help improve performance by allowing us to transform data directly within the template, reducing the need for intermediate data transformations in component logic.

  • Readability: Pipes improve the readability of our templates by providing a declarative way to transform data directly within the template. This allows the developers to understand the intention of the data transformation without needing to dig into the component logic.

  • Code Reusability: Pipes allow us to encapsulate data transformation logic in a reusable and modular way. Once defined, pipes can be used in multiple components and templates throughout our application, promoting code reuse and reducing duplication.

  • Internationalization (i18n) and Localization (l10n): Angular provides built-in pipes such as DatePipe, CurrencyPipe, and DecimalPipe, which automatically handle formatting based on the locale.

  • Maintainability: By encapsulating data transformation logic within pipes, we can keep our component templates clean and focused on presentation logic.

  • Consistency: Pipes help enforce consistent data formatting and manipulation across our application. By centralizing transformation logic within pipes, we can ensure that data is displayed consistently throughout our application, regardless of where it is used.

Built-in Pipes:

Angular provides several built-in pipes that we can use out of the box:

Uppercase Pipe:

Transforms text to all uppercase.

Example:

<!-- Example -->
<p>{{ 'welcome' | uppercase }}</p> <!-- Output: WELCOME -->
<p>{{ 'WelCome' | uppercase }}</p> <!-- Outputs: WELCOME -->

Lowercase Pipe:

Example:

<!-- Example -->
<p>{{ 'WELCOME' | lowercase }}</p> <!-- Outputs: welcome -->
<p>{{ 'WelCome' | lowercase }}</p> <!-- Outputs: welcome -->

Transforms text to all lowercase.

Example:

<!-- Example -->
<p>{{ 3.14159265359 | number:'1.2-2' }}</p> <!-- Outputs: 3.14 -->

Decimal Pipe:

Example:

<!-- Example -->
<p>{{ today | date:'short' }}</p> <!-- Outputs: 30/01/2022 -->

Formats a number as a decimal number.

Example:

<!-- Example -->
<p>{{ 0.40 | percent }}</p> <!-- Outputs: 40% -->

Date Pipe:

Example:

import { Pipe, PipeTransform } from '@angular/core';

@Pipe({
  name: 'yourCustomPipe'
})
export class YourCustomPipe implements PipeTransform {
  transform(value: any, ...args: any[]): any {
    // Custom transformation logic
    return ...;
  }
}

Example:

<!-- Example -->
<p>{{ someValue | yourCustomPipe }}</p>

Formats a date value according to the locale rules.

Example:

<!-- Example -->
<p>{{ myDate | date | uppercase }}</p>

Percent Pipe:

Formats a number as a percentage.

Custom Pipe:

We can also create custom pipes for more specialized data transformations.

Then we can use our custom pipe in your templates:

Chaining Pipes:

We can chain multiple pipes together in the template for more complex transformations:

Conclusion:

  • Pipes in Angular are a powerful feature for transforming data directly within your templates.

  • They provide a convenient way to format, filter, and manipulate data before displaying it to users.

  • Angular's built-in pipes cover many common use cases, and we can easily create custom pipes to meet specific formatting needs in your application.

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