javascript - Check if textarea already exist -

how check if textarea exists in javascript:

i have 2 radio button:

yes , no 

if yes click call javascript function showtxtbox(); , if no call removetxtbox();

showtxtbox() - creates textarea if radio button yes clicked. removetxtbox() - remove textarea if radio button no clicked.

<script type="text/javascript">     function showtxtbox()         {             var p = document.getelementbyid("txtarea");             var textarea = document.createelement('textarea');             textarea.id = "txtrelativeans";             textarea.setattribute('rows', '4');             textarea.setattribute('cols', '50');             p.appendchild(textarea);         }     function removetxtbox()         {             var p = document.getelementbyid("txtarea");             var textarea = document.getelementbyid('txtrelativeans');             p.removechild(textarea);         }  </script> 

my problem is, when radio button yes click twice. create 2 textarea.. how can check if textarea exist.. if yes no longer create textarea.

thanks!

<script type="text/javascript">     function showtxtbox()         {             var p = document.getelementbyid("txtarea");             if(!document.getelementbyid("txtrelativeans")) {                 var textarea = document.createelement('textarea');                 textarea.id = "txtrelativeans";                 textarea.setattribute('rows', '4');                 textarea.setattribute('cols', '50');                 p.appendchild(textarea);             }         }     function removetxtbox()         {             var p = document.getelementbyid("txtarea");             var textarea = document.getelementbyid('txtrelativeans');             p.removechild(textarea);         }  </script>