ValueChange in TextArea of Telerik Blazor dialog

I have a Telerik dialogblog in which I have added one telerikTextArea i want to show the number of character in textarea dynamically whenever value changed in textarea its character count should be shown on display.

Here is my code

.razor

 
   
                 
                                     
       
   
   
        Save
        Close
   

@code

{

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;
using EDMS.DSM.Shared;
using EDMS.DSM.Shared.Dto;
using EDMS.Evaluations.Client.Managers;
using Microsoft.AspNetCore.Components;
using Microsoft.AspNetCore.Components.Forms;
using Microsoft.JSInterop;

namespace EDMS.Evaluations.Client.Pages.Evaluation.EvaluationDetails;
public partial class EditNotes :ComponentBase
{
  [Parameter] public EventCallback OnHidden {  get; set; }
  [Parameter] public bool isVisible { get; set; }
  [Parameter] public string HeaderName { get; set; }
  [Parameter] public string InternalNote { get; set; }
  [Parameter] public string CustomerNote { get; set; }
  [Inject] private TestData _testData { get; set; } = default!;
  [Parameter] public long MeasureId { get; set; }
  [Inject] public IEvaluations evaluationsManager { get; set; } = default!;
 

  public string Notes { get; set; }

  public int characterCount { get; set; } = 0;

  protected override async Task OnParametersSetAsync()
  {
    if (isVisible)
    {
      Notes = HeaderName.Contains("Internal")? InternalNote:CustomerNote;
    }
  }
    
  public async void SaveEditedNotes()
  {
    if(HeaderName.Contains("Internal"))
    {
      InternalNote = Notes;
    }
    else if(HeaderName.Contains("Customer"))
    {
      CustomerNote= Notes;
    }
    SaveEval_InspEditedNotesRequestDto request = new SaveEval_InspEditedNotesRequestDto()
    {
      ProjectId=_testData.ProjectId,
      AdvisorId=_testData.ByUserID,
      MeasureId=MeasureId,      
      UnitNotes=InternalNote,
      UnitCustomerNotes=CustomerNote,      
    };

    var result = await evaluationsManager.SaveEval_InspNote(request);

    _ = OnHidden.InvokeAsync();
  }

  public void Close()
  {
    isVisible= false;
    _ = OnHidden.InvokeAsync();
  }

}
 

}