Javascript Counter

function textCounter(field,cntfield,maxlimit)
{
if (field.value.length > maxlimit) // if too long...trim it!
field.value = field.value.substring(0, maxlimit);
else
cntfield.value = maxlimit - field.value.length;
}
function update()
{
var limit =10;
var message = document.getElementById('message2').value;
var old = document.getElementById('txtcounter2').value;
document.getElementById('txtcounter2').value=message.length;
if(document.getElementById('txtcounter2').value > limit && old <= limit)
{
alert('Too much data in the text box!');
if(document.styleSheets)
{
document.getElementById('txtcounter2').style.fontWeight = 'bold';
document.getElementById('txtcounter2').style.color = '#ff0000';
}
}
else if(document.getElementById('txtcounter2').value <= limit && old > limit && document.styleSheets )
{
document.getElementById('txtcounter2').style.fontWeight = 'normal';
document.getElementById('txtcounter2').style.color = '#000000';
}
}
onkeyup="textCounter(this,txtcount1,125)">
onkeyup=update();