title: how to have undeletable words(part of text) in textarea
body: <p>I am developing an application which needs a part of text in the textarea undeletable while they can add their text to the <code>textarea</code>. </p>
  
  <p>For example when user come to a web page it has a textarea which has a text <code>{username}</code> of that user. The user can add more text like <code>{username} hi the the earth is globe</code> but should be unable to delete <code>{username}</code> from that textarea.</p>
  
  <p>I am using Jquery as the javascript class, any idea that we can achieve it in Jquery?</p>