How to implement a pipe that calculates the age from a birthdate input

Question

Can you tell me How to implement a pipe that calculates the age from a birthdate input?

Answer 1

To implement a custom pipe that calculates age from a birthdate in Angular:

Step 1: Create the Pipe

ng generate pipe age

Step 2: Implement Logic in Pipe

typescript

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

@Pipe({ name: 'age' })

export class AgePipe implements PipeTransform {

  transform(value: Date | string): number {

    const birthDate = new Date(value);

    const today = new Date();

    let age = today.getFullYear() - birthDate.getFullYear();

    const m = today.getMonth() - birthDate.getMonth();

    if (m < 0 || (m === 0 && today.getDate() < birthDate.getDate())) {

      age--;

    }

    return age;

  }

}

Step 3: Use in Template

<p>Age: {{ user.birthdate | age }}</p>