Need to fix this code

[vividona]

my smileys inserted verygood in textarea. But if you delete smiley code and need to insert new one the previous code will be there.

<script type="text/javascript"> 
    function insertSmiley(smiley) 
    { 
        var currentText = document.getElementById("message"); 
        var smileyWithPadding = " " + smiley + " "; 
        currentText.innerHTML += smileyWithPadding; 
    } 
</script>
<textarea name="message" rows="5" id="message"></textarea>

<img src="interface/bigSmile.gif"     onclick="insertSmiley(':-D')" /><br>
<img src="interface/cantLook.gif"     onclick="insertSmiley(':-P')" />
<img src="interface/cry.gif"          onclick="insertSmiley(':=(')" />
<img src="interface/devious.gif"      onclick="insertSmiley('=')" />
<img src="interface/huh.gif"          onclick="insertSmiley('o_0')" />
<img src="interface/knockedOut.gif"   onclick="insertSmiley('x-)')" />
<img src="interface/puzzled.gif"      onclick="insertSmiley(':-~')" />
<img src="interface/regularSmile.gif" onclick="insertSmiley(':-)')" />
<img src="interface/shocked.gif"      onclick="insertSmiley(':-o')" />
<img src="interface/snooze.gif"       onclick="insertSmiley('z:-)')" />
<img src="interface/tongue.gif"       onclick="insertSmiley(':-P')" />
<img src="interface/unsure.gif"       onclick="insertSmiley(':-/')" />
<img src="interface/upset.gif"        onclick="insertSmiley(':-(')" />