function reverse() {
text = "";
str = document.forms[0].elements[0].value=document.forms[0].elements[0].value;
for (i = 0; i <= str.length; i++)
text = str.substring(i, i+1) + text;
document.forms[0].elements[0].value = document.forms[0].elements[0].value = text;
}
This will reverse any text that you enter into it.