Let’s say in your ASP.NET application you set a TextBox control’s property ReadOnly to True (or Enabled to False) to prevent user from entering data directly. But you still want to update that text box’s value via client-side JavaScript. Which is happening, the value can be updated. But during postback to the server – surprise, surprise! – the new value doesn’t persist. This is due to security precaution – if the value wasn’t meant to be changed – the change is not allowed. But there is a way around this.