<html>
<head>
<title>Calculate Fahrenheit/Celsius</title>
<meta charset="utf-8" />
</head>
<body>
<form name="myform">
Temperature: <input type="text" name="temperature" value="0" /><br/><br/>
<input type="radio" name="switch" id="c2f" value="1" /> C -> F <br/>
<input type="radio" name="switch" id="f2c" value="2" checked="checked" /> F -> C<br/>
<br/>
<button name="btn_calculate" onclick="javascript:calculate();">Calculate</button>
</form>
<script>
function calculate() {
var temperature = document.forms['myform']['temperature'].value;
if (document.getElementById('f2c').checked) {
var c = 0.56 * (temperature - 32);
alert("Temperature in C is: " + c);
} else {
var f = (temperature * 1.8) + 32;
alert("Temperature in F is: " + f);
}
}
</script>
</body>
</html>