<script>
function foo(){
   var textbox=  document.getElementById('target');
   selectText(textbox,0,14);
}
function selectText(textbox,startIndex,stopIndex){
     if(textbox.setSelectionRange){
           textbox.setSelectionRange(startIndex,stopIndex); 
     }else if(textbox.createTextRange){
         var range=textbox.createTextRange();
         range.collapse(true);
         range.moveStart('character',startIndex);
         range.moveEnd('character',stopIndex-startIndex);
         range.select();
     }
     textbox.focus();
}
</script>
<textarea cols="40" rows="10" id="target">
<div>php</div>
<div>qqq</div>
</textarea>
<input type="button" onclick="foo()" value="Click">