Membuat Kalkulator Pada Web

<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" 

"http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml">
<head>
<meta http-equiv="Content-Type" content="text/html; charset=utf-8" />
<title>Jefri-UPI</title>
</head>

<body>

<p align="center"> Kalkulator Sederhana </p>
<p align="center">    Design By Jefri Fernando </p>
<script type="text/javascript">

//fungsi penjumlahan
function tambah()
{
    var a = parseFloat(document.arz.nilaisatu.value);
    if(isNaN(a))
    {
        a=0.0;
    }
    var b = parseFloat(document.arz.nilaidua.value);
    if(isNaN(b))
    {
        b=0.0;
    }

    var tambah = a+b;
    alert("Hasil Penjumlahan antara bilangan" + a + "dan bilangan" + b + "adalah = 

" + tambah );
}

//fungsi pengurangan
function kurang()
{
    var a= parseFloat(document.arz.nilaisatu.value);
    if(isNaN(a))
    {
        a=0.0;
    }
    var b= parseFloat(document.arz.nilaidua.value);
    if(isNaN(b))
    {
        b=0.0;
    }

    var kurang = a-b;
    alert(" Hasil Pengurangan antara bilangan " + a + "dan bilangan" + b +"adalah 

= " + kurang );
}

//fungsi perkalian
function kali()
{
    var a = parseFloat(document.arz.nilaisatu.value);
    if(isNaN(a))
    {
        a=0.0;
    }
    var b = parseFloat (document.arz.nilaidua.value);
    if(isNaN(b))
    {
        b=0.0;
    }

    var kali = a*b;
    alert("Hasil Perkalian antara bilangan " + a + "dan bilngan" + b +"adalah = " 

+ kali);
}

//fungsi pembagian
function bagi()
{
    var a= parseFloat(document.arz.nilaisatu.value);
    if(isNaN(a))
    {
        a=0.0;
    }
    var b= parseFloat(document.arz.nilaidua.value);
    if(isNaN(b))
    {
        b=0.0;
    }

    var bagi = a/b;
    alert("Hasil Pembagian antara bilangan " + a + "dan bilngan" + b + "adalah = " 

+ bagi );
}


</script>

<form name="arz">
<div align="center">
<pre>
Nilai A = <input type="text" name="nilaisatu" />
Nilai B = <input type="text" name="nilaidua" />
</pre>
<input type="button" name="Hitung" value="Kali" onclick="kali()" />
     <input type="button" name="hitung" value="Bagi" onclick="bagi()" />
<input type="button" name="hitung" value="Jumlah" onclick="tambah()" />
    <input type="button" name="hitung" value="Kurang" onclick="kurang()" />
<input type="reset" name="clear" value="Bersih" />

</div>
</form>

</body>
</html>