How to add a mask 'yyyy/yyyy' in angular2, using pipe and formatter to input field

Question

I'd like to know how can I create a mask with regex expression for input field.

I need to add some masks to a field, such as: yyyy/yyyy. This sounds like a period.

I saw a link that creates a mask using the pipe from Angular2. Here is the link.

So, I'd like to create a pipe with a different regex expression to allow the user writes only this: yyyy/yyyy ; and using transform method from pipe. Is this possible?

Here is my pipe and formatter:

import { Pipe, PipeTransform } from "@angular/core";
@Pipe({ name: "mypipe" })
export class MyPipe implements PipeTransform {
  private SEPARATOR: string;
  constructor() {
    this.SEPARATOR = "/";
  }
  transform(value): string {
    let integer = (value || "").toString();
    // Here is where the code should be, to transform the value
    return integer;
  }
  transform(value): string {
    // parse method
  }
}

import { Directive, HostListener, ElementRef, OnInit } from "@angular/core";
// import { MyPipe } from ...
@Directive({ selector: "[myFormatter]" })
export class MyFormatterDirective implements OnInit {
  private el: HTMLInputElement;
  constructor(
    private elementRef: ElementRef,
    private mypipe: MyPipe
  ) {
    this.el = this.elementRef.nativeElement;
  }
  ngOnInit() {
    this.el.value = this.mypipe.transform(this.el.value);
  }
  @HostListener("keydown", ["$event.target.value"])
  handleKeyboardEvent(value) {
    this.el.value = this.mypipe.transform(value);
  }
}