How to read formControlRange Value after pressing a button

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if we use TIWBS4Region with RawText and Text Property
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<label for="formControlRange">Example Range input</label>
<input type="range" min="1" max="100" value="20" class="form-control-range" id="formControlRange">
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How to read formControlRange Value after pressing a button?
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object IWForm2: TIWForm2
  Left = 0
  Top = 0
  Width = 979
  Height = 438
  RenderInvisibleControls = True
  AllowPageAccess = True
  ConnectionMode = cmAny
  Background.Fixed = False
  LayoutMgr = IWBS4LayoutMgr1
  HandleTabs = False
  LeftToRight = True
  LockUntilLoaded = True
  LockOnSubmit = True
  ShowHint = True
  JavaScript.Strings = (
   
      '$(document).ready(function(){$('#39'[data-toggle="tooltip"]'#39').toolti' +
      'p();});')
  DesignLeft = 2
  DesignTop = 2
  object IWBS4Region2: TIWBS4Region
    Left = 56
    Top = 24
    Width = 825
    Height = 353
    Css = ''
    HeightRender = False
    Text = ''
    WidthRender = False
    BSRegionType = bs4rtContainer
    object IWBS4Button1: TIWBS4Button
      Left = 32
      Top = 176
      Width = 200
      Height = 25
      ScriptInsideTag = False
      OnAsyncClick = IWBS4Button1AsyncClick
      IconOnRight = False
      Caption = 'ReadSlideValue'
      ModalKeyboardEscape = False
      Tooltip.Delay = 0
      Tooltip.Trigger = 'focus hover'
    end
    object IWBS4Region1: TIWBS4Region
      Left = 32
      Top = 35
      Width = 713
      Height = 121
      Css = ''
      HeightRender = True
      RawText = True
      Text =
        '<label for="formControlRange">Example Range input</label>'#13#10'<inpu' +
        't type="range" min="1" max="100" value="20" class="form-control-' +
        'range" id="formControlRange">'
      WidthRender = True
      BSRegionType = bs4rtFormGroup
    end
  end
  object IWBS4LayoutMgr1: TIWBS4LayoutMgr
    Left = 704
    Top = 216
  end
end