The formula four kinds of repayment of their own to Baidu
Equal monthly installments of principal and interest repayment method, see:
https://baike.baidu.com/item/%E7%AD%89%E9%A2%9D%E6%9C%AC%E6%81%AF/3227456
Debt service due process, see:
Monthly interest due principal method as follows:
Each time (does not include the last time) repayment amount: × total lending interest rate on
the last repayment amount: × total lending interest rate on total loans +
By April principal and interest equal law:
With equal monthly installments of principal and interest is the same, details of code
Directly on the source code:
<!DOCTYPE html>
<html lang="zh-cn">
<head>
<meta charset="UTF-8">
<title>还款计算器</title>
</head>
<style>
td{
text-align:center;
}
</style>
<body>
<p>金额：</p>
<p><input type="text" value='' name="account" id='account'></p>
<p>年利率：</p>
<p><input type="text" value='' name="apr" id='apr'></p>
<p>期限：</p>
<p>
<select name="time_limit" id="time_limit">
<option value="1">1个月</option>
<option value="2">2个月</option>
<option value="3">3个月</option>
<option value="4">4个月</option>
<option value="5">5个月</option>
<option value="6">6个月</option>
<option value="7">7个月</option>
<option value="8">8个月</option>
<option value="9">9个月</option>
<option value="10">10个月</option>
<option value="11">11个月</option>
<option value="12">12个月</option>
</select>
</p>
<p>还款方式：</p>
<p>
<select name="type" id="type">
<option value="1">按月等额本息</option>
<option value="3">到期还本按月付息</option>
<option value="4">到期还本付息</option>
</select>
</p>
<p><button type='button' id="cal">计算</button></p>
<table border='1px' cellspacing="0" width='700px' id='table'>
</table>
</body>
<script>
var account = document.getElementById('account');
var apr = document.getElementById('apr');
var time_limit = document.getElementById('time_limit');
var typeObj = document.getElementById('type');
var cal = document.getElementById('cal');
var table = document.getElementById('table');
var money = account.value; //借款金额
var year_apr = (apr.value)/100; //年利率
var period = time_limit.value;//借款期限
var type = typeObj.value; //还款方式
var month_apr = year_apr/12; //月利率
time_limit.onchange = function(){
period = time_limit.value;
if(period==8){
typeObj.options.add(new Option('按4月等额本息',2));
}else{
typeObj.options.remove(3);
}
}
cal.onclick=function(){
money = account.value; //借款金额
year_apr = (apr.value)/100; //年利率
period = time_limit.value;//借款期限
type = typeObj.value; //还款方式
month_apr = year_apr/12; //月利率
str=_cal(money,period,type,month_apr);
if(str!=false){
table.innerHTML=str;
}
}
/**
* @param money 借款金额
* @param period 借款期限
* @param type 还款方式 1 按月等额本息 2 按4月等额本息 3 到期还本按月付息 4 到期还本付息
* @param month_apr 月利率
* @return string
*/
function _cal(money,period,type,month_apr){
var interest_tot = 0; //预期收益
var repayment_tot = 0; //本息合计
if(false == isNumber(money)){
alert('借款金额格式错误');
return false;
}
if(false == isNumber(month_apr)){
alert('年利率格式错误');
return false;
}
if(0 == money || money < 0){
alert('借款金额不能小于或者等于0');
return false;
}
if(0 == month_apr || month_apr < 0){
alert('年利率不能小于或者等于0');
return false;
}
var str = '<tr>\
<th>期数</th>\
<th>回款本息</th>\
<th>回款本金</th>\
<th>利息</th>\
</tr>';
//每月还款额
if(type == 1){
repayment = (money * month_apr * Math.pow((1 + month_apr),period))/(Math.pow((1 + month_apr),period) - 1);
for (var i = 1 ; i <=period ; i++) {
capital = (money * month_apr * Math.pow((1 + month_apr),i - 1))/(Math.pow((1 + month_apr),period) - 1);
repayment_a = repayment.toFixed(2);
capital = capital.toFixed(2);
interest_a = (repayment_a - capital).toFixed(2);
interest_tot+=interest_a*1; //预期收益
repayment_tot+=repayment_a*1//本息合计
//月收本息
str+='<tr>\
<td>'+i+'</td>\
<td>'+repayment_a+'</td>\
<td>'+capital+'</td>\
<td>'+interest_a+'</td>\
</tr>';
}
str+='<tr><td colspan="4">预期收益：'+interest_tot.toFixed(2)+' 本息合计：'+repayment_tot.toFixed(2)+' 月收本息：'+repayment_a+'</td></tr>';
}else if(type == 2){
month_apr_new = month_apr * 4;
period_new = period / 4;
repayment = (money * month_apr_new * Math.pow((1 + month_apr_new),period_new))/(Math.pow((1 + month_apr_new),period_new) - 1);
for (var i = 1 ; i <=period_new ; i++) {
capital = (money * month_apr_new * Math.pow((1 + month_apr_new),i - 1))/(Math.pow((1 + month_apr_new),period_new) - 1);
repayment_a = repayment.toFixed(2);
capital = capital.toFixed(2);
interest_a = (repayment_a - capital).toFixed(2);
str+='<tr>\
<td>'+i+'</td>\
<td>'+repayment_a+'</td>\
<td>'+capital+'</td>\
<td>'+interest_a+'</td>\
</tr>';
}
}else if(type == 3){
interest_a = (money * month_apr).toFixed(2);
for (var i = 1 ; i <=period ; i++) {
capital = 0;
repayment_a = interest_a;
if (i == period){
capital = money;
repayment_a = interest_a*1 + capital*1;
}
str+='<tr>\
<td>'+i+'</td>\
<td>'+repayment_a+'</td>\
<td>'+capital+'</td>\
<td>'+interest_a+'</td>\
</tr>';
}
}else if(type == 4){
//贷款本金×[1+月利率（‰）×贷款期（月）]
repayment = money * (1 + month_apr * period);
repayment_a = repayment.toFixed(2);
interest_a = (repayment_a - money).toFixed(2);
str+='<tr>\
<td>第'+period+'个月</td>\
<td>'+repayment_a+'</td>\
<td>'+money+'</td>\
<td>'+interest_a+'</td>\
</tr>';
}else{
str = '不存在';
}
return str;
}
function isNumber(val){
var regPos = /^\d+(\.\d+)?$/; //非负浮点数
var regNeg = /^(-(([0-9]+\.[0-9]*[1-9][0-9]*)|([0-9]*[1-9][0-9]*\.[0-9]+)|([0-9]*[1-9][0-9]*)))$/; //负浮点数
if(regPos.test(val) || regNeg.test(val)){
return true;
}else{
return false;
}
}
</script>
</html>