How to convert numbers to words using javascript?

// American Numbering System
var th = ['','thousand','million', 'billion','trillion'];
// uncomment this line for English Number System
// var th = ['','thousand','million', 'milliard','billion'];

var dg = ['zero','one','two','three','four', 'five','six','seven','eight','nine'];
var tn = ['ten','eleven','twelve','thirteen', 'fourteen','fifteen','sixteen', 'seventeen','eighteen','nineteen'];
var tw = ['twenty','thirty','forty','fifty', 'sixty','seventy','eighty','ninety'];
function toWords(s)
{
s = document.getElementById(s.id).value; //Source Control
//s = s.toString();
s = s.replace(/[\, ]/g,'');
if (s != String(parseFloat(s)))
return 'not a number';
var x = s.indexOf('.');
if (x == -1) x = s.length;
if (x > 15)
return 'too big';
var n = s.split('');
var str = '';
var sk = 0;
for (var i=0; i < x; i++)
{
if ((x-i)%3==2)
{
if (n[i] == '1')
{
str += tn[Number(n[i+1])] + ' ';
i++; sk=1;
}
else if (n[i]!=0)
{
str += tw[n[i]-2] + ' ';
sk=1;
}
}
else if (n[i]!=0)
{
str += dg[n[i]] +' ';
if ((x-i)%3==0)
str += 'hundred ';
sk=1;
}
if ((x-i)%3==1)
{
if (sk)
str += th[(x-i-1)/3] + ' ';
sk=0;
}
}
if (x != s.length)
{
var y = s.length;
str += 'point ';
for (var i=x+1; i str += dg[n[i]] +' ';
}
document.getElementById('TxtWords').value=str.replace(/\s+/g,' ') +' ' + 'rupees only'; //TargetControl
//return str.replace(/\s+/g,' ');
}