Credit calculator(ua-ru)

/* js code */
// Credit calculator
function elems_summ(arr) {
	var total = 0;
	for (var i=1; i < arr.length; i++) {
		total += arr[i];
	}
	return total.toPrecision(7);
}

function calculate() {
	// datas for calculation
	var price = $("input#price").val();
	var vznos = $("input#vznos").val();
	var period = $("select#period").val();
	var stavka = $("input#stavka").val();
	
	var percents = new Array();
	var m = '';
	var html = '';
	var price_glob = price;
	var credit_summ = price;
	
	if (vznos != 0) {
		price -= vznos;
		credit_summ = price;
	}
	
	var f1 = $("input#forma1:checked").val();
	if (f1 == 1) {
		// anual credit
		var mounthly = price * (((stavka/100)/12)/(1-(Math.pow(1+((stavka/100)/12), -period))));
		m = mounthly.toPrecision(7)
		for (var i=1; i <= period; i++) {
			var percent = (price * (stavka/12) / 100);
			percents[i] = percent;
			var body = m - percent;
			html += '<tr><td>'+i+'</td><td>'+parseFloat(price).toPrecision(7)+'</td><td>'+body.toPrecision(7)+'</td><td>'+percent.toPrecision(7)+'</td><td>'+m+'</td></tr>';
			price -= body;
		}
	} else {
		// standart credit
		var body = price / period;
		var average_pay = 0;
		for (var i=1; i <= period; i++) {
			var percent = (price * (stavka/12) / 100);
			var mounthly = body + percent;
			average_pay += mounthly;
			percents[i] = percent;
			html += '<tr><td>'+i+'</td><td>'+parseFloat(price).toPrecision(7)+'</td><td>'+body.toPrecision(7)+'</td><td>'+percent.toPrecision(7)+'</td><td>'+mounthly.toPrecision(7)+'</td></tr>';
			price -= body;
		}
		m = average_pay / period;
	}
	var percents_summ = elems_summ(percents);
	var full_summ = parseFloat(credit_summ) + parseFloat(percents_summ);
	$("div#result").html("<div id='estimate'>Цена автомобиля, USD:&nbsp;"+price_glob+
						 "<br />Сумма кредита, USD:&nbsp;"+credit_summ+
						 "<br />Сумма выплаченных процентов за весь срок, USD:&nbsp;"+percents_summ+
						 "<br />Среднемесячный полный платеж, USD:&nbsp;"+m+
						 "<br />Полная стоимость с учетом выплаченных процентов, USD:&nbsp;"+full_summ+"</div>")
	var tbl = $("input#table:checked").length;
	if (tbl) {
		$("div#estimate").after("<table border='1' id='est'><tr><td>Месяц</td><td>Остаток кредита</td><td>Тело кредита</td><td>Начислено процентов</td><td>Всего к оплате</td></tr>"+html+"</table>");
	}
	
	$("#clean").click(function () {
		$("div#estimate").remove();
		$("table#est").remove();
	})
}


/* template */
{% extends "base.html" %}
{% load i18n %}

{% block title %}
	{% trans "Credit calculator" %}
{% endblock %}

{% block scripts %} 
<script type="text/javascript" src="{{ MEDIA_URL }}js/credit.js"> </script>
{% endblock %}

{% block content %}
	<h2>{% trans "Credit calculator" %}</h2>
	<table width="300" cellspacing="0" cellpadding="3" border="0">
		<tbody>
		<tr>
			<td nowrap="nowrap"> <strong>{% trans "Price of auto in USD" %}:</strong></td>
			<td nowrap="nowrap">
				<input type="text" value="0" id="price" name="price" class="required" maxlength="6" /><strong>$</strong>
				<input type="hidden" value="" id="price" name="price"/>
			</td>
		</tr>

		<tr>
			<td><strong>{% trans "Start payment" %}<span id="vznos_proc"/>:</strong></td>
			<td nowrap="nowrap">
				<input type="text" id="vznos" name="vznos" value="0" class="required" maxlength="6" /><strong>$</strong>
			</td>
		</tr>
		<tr>
			<td nowrap="nowrap"><strong>{% trans "Credit period" %}:</strong></td>
			<td>
				<select id="period" name="period" type="text" class="required">
					<option value="12">{% trans "year" %}</option>
					<option value="24">{% trans "2 year" %}</option>
					<option value="36">{% trans "3 year" %}</option>
					<option value="48">{% trans "4 year" %}</option>
					<option selected="selected" value="60">{% trans "5 year" %}</option>
					<option value="84">{% trans "6 year" %}</option>
				</select>
			</td>
		</tr>
		<tr>
			<td> <strong>{% trans "Annual bank salary" %}:</strong></td>
			<td nowrap="nowrap">
				<input type="text" id="stavka" name="stavka" value="12" style="width: 60px;" maxlength="6"/><strong>%</strong>
			</td>
		</tr>
		<tr>
			<td>&nbsp;<strong>{% trans "Form of credit repayment" %}:</strong></td>
			<td>&nbsp;</td>
		</tr>
		<tr>
			<td colspan="2">
				<table>
					<tbody>
						<tr>
							<td>&nbsp;
								<input type="radio" value="1" id="forma1" name="forma" checked="checked"/>
							</td>
							<td>&nbsp;
								<label for="forma1">{% trans "Annua" %} ({% trans "equal parts" %})</label>
							</td>
							<td>
								<input type="radio" value="2" id="forma2" name="forma"/>
							</td>
							<td>
								<label for="forma2">{% trans "standart" %}</label>
							</td>
						</tr>
					</tbody>
				</table>
			</td>
		</tr>
		<tr>
			<td colspan="2">
				<input type="checkbox" align="absmiddle" value="yes" id="table" name="table" />{% trans "calculate monthly instalments" %}
			</td>
		</tr>
		<tr>
			<td colspan="2"><br/>
				<input type="button" value="{% trans 'Clean' %}" id="clean" />&nbsp;
				<input type="button" value="{% trans 'Calculate' %}" id="countb" name="" onclick="calculate()" />
			</td>
		</tr>
		</tbody>
	</table>
	<div id="result"> </div>
{% endblock %}