Stringify JavaScript

This code reads selected text after a user releases the mouse button. I came up with this technique after I read a questions at Stack Overflow. I never actually used it on any web projects, but it might come in handy at a later time.
 
IE uses the native createRange(); method and Webkit can use the getSelection(); method of the window or document object.

JavaScript:
 

document.onmouseup = function() {

   var txt = ' ';

   // Webkit
   if (window.getSelection) {
      txt = window.getSelection();
   }

   // Webkit Alternative
   else if (document.getSelection) {
      txt = document.getSelection();
    }

   // IE
   else if (document.selection) {
      txt = document.selection.createRange().text;
   }

   // if no selection then break here
   else return;

   document.someForm.selectedtext.value = txt;
}

Markup:
 

<form name="someForm">  
    <textarea name="selectedtext" rows="5" cols="20"></textarea>
</form>

View an example of this technique here: TextSelect Example