How to display a comma only in an input?

In the input HTML, currently, the user can enter multiple commas, I would like to reduce the number of commas by 1. I d’ont know how to make this?

For example: The user cannot enter 20......01 but only 20.01


<input notdot maxlength="5" [(ngModel)]="value" />


export class AppComponent  {


  imports: [BrowserModule, FormsModule],
  declarations: [AppComponent, NotDotDirective],
  bootstrap: [AppComponent],
export class AppModule {}


import { Directive,Injector,HostListener,Optional,Host } from '@angular/core';
import {NgControl} from '@angular/forms'
  selector: '[notdot]'
export class NotDotDirective {

  constructor(@Optional() @Host()private control:NgControl) {}
  @HostListener('input', ['$event'])
  change($event) {

    const item = $
    const value = item.value;
    const pos = item.selectionStart; //get the position of the cursor

    const matchValue = value.replace(/,/g, '.')
    if (matchValue!=value)
      if (this.control)
        this.control.control.setValue(matchValue, { emit: false });

      item.value = matchValue;
      item.selectionStart = item.selectionEnd = pos; //recover the position

Here is a reproduction -> here. If you have a solution, I am really interested.

Thank you very much for your help.

>Solution :

On your directive you can change line 20 with:

const matchValue = value.replace(/,/g, '.').replace(/\.\./, '.');

You are replacing comma with dots and if you insert more than one dot, it replaces the input with just only one

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