Собрался сделать калькулятор для сайта провайдера ,но он не работает, помогите решить проблему пожалуйста
[JS]
<script>
function calc() {
var type_design = document.getElementById("type_design");
var is_html = document.getElementById("is_html");
var is_html1 = document.getElementById("is_html1");
var is_html2 = document.getElementById("is_html2");
var is_html3 = document.getElementById("is_html3");
var month3 = document.getElementById("month3");
var month6 = document.getElementById("month6");
var month12 = document.getElementById("month12");
var result = document.getElementById("result");
var price = 0;
price += parseInt(type_design.options[type_design.selectedIndex].value);
price += (is_html.checked == true) ? parseInt(is_html.value) : 0;
price += (is_html1.checked == true) ? parseInt(is_html1.value) : 0;
price += (is_html2.checked == true) ? parseInt(is_html2.value) : 0;
price += (is_html3.checked == true) ? parseInt(is_html3.value) : 0;
price *= (month3.checked == true) ? parseInt(month3.value) : 0;
price *= (month6.checked == true) ? parseInt(month6.value) : 0;
price *= (month12.checked == true) ? parseInt(month12.value) : 0;
result.innerHTML = price;
}
</script>
[/JS]
</head>
<body>
<b>Калькулятор цен</b><br/>
<select onchange="calc()" id="type_design">
<option value="0" selected>Выберите тариф</option>
<option value="900">Тариф1</option>
<option value="1200">Тариф2</option>
<option value="1900">Тариф3</option>
</select><br/>
<label for="is_html">
<input type="radio" onchange="calc()" name="first" value="0" id="is_html" checked="checked"/>
Без опций</label>
<br/>
<label for="is_html1">
<input type="radio" onchange="calc()" name="first" value="100" id="is_html1" /> Пакет 1</label>
<br/>
<label for="is_html2">
<input type="radio" onchange="calc()" name="first" value="175" id="is_html2" />
Пакет 2</label>
<br/>
<label for="is_html3">
<input type="radio" onchange="calc()" name="first" value="250" id="is_html3" />
Пакет 3</label>
<br/>
<label for="month1">
<input type="radio" onchange="calc()" name="month_col" value="1" id="month1" checked="checked"/>
1 Месяц</label>
<br/>
<label for="month3">
<input type="radio" onchange="calc()" name="month_col" value="3" id="month3"/>
3 Месяца</label>
<br/>
<label for="month6">
<input type="radio" onchange="calc()" name="month_col" value="6" id="month6"/>
6 Месяцев</label>
<br/>
<label for="month12">
<input type="radio" onchange="calc()" name="month_col" value="12" id="month12"/>
12 Месяцев</label>
<br/>
<div>Стоимость: <span id="result">0</span> руб.</div>
</body>