angular pipeline

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

@Pipe({
  name: 'multi'
})
export class MultiPipe implements PipeTransform {

  transform(value: any, args?: any): any {
    if (args == null) {
      args = 1;
    }
    return value * args;
  }

}

<div>My birthday{{birth | date | uppercase}}</div>
<div>My birthday{{birth | date : ' yyyy-MM-dd ' }}</div>
<div>My Birthday{{numberA | number : ' 2.1-4 ' }}</div>

<div>My Birthday{{numberA | multi : 2 }}</div>

import { Component, OnInit } from '@angular/core';

@Component({
  selector: 'app-bind',
  templateUrl: ' ./bind.component.html ' ,
  styleUrls: ['./bind.component.css']
})
export class BindComponent implements OnInit {

  private birth: Date;

  private numberA: number;

  constructor() { }

  by OnInit () {
    this.birth = new Date();
    this.numberA = 3.1514926;
  }
}