写一个web实现房贷计算等额本息、等额本金计算

可以使用JavaScript编写一个简单的房贷计算器。以下是等额本息和等额本金计算的示例代码：

等额本息计算：

function calculateEqualPrincipalAndInterest(totalAmount, years, rate) {
  var monthlyRate = rate / 12;
  var totalMonths = years * 12;
  var monthlyPayment = totalAmount * monthlyRate * Math.pow(1 + monthlyRate, totalMonths) / (Math.pow(1 + monthlyRate, totalMonths) - 1);
  var totalPayment = monthlyPayment * totalMonths;
  var interest = totalPayment - totalAmount;
  
  return {
    monthlyPayment: monthlyPayment.toFixed(2),
    totalPayment: totalPayment.toFixed(2),
    interest: interest.toFixed(2)
  };
}

等额本金计算：

function calculateEqualPrincipal(totalAmount, years, rate) {
  var monthlyRate = rate / 12;
  var totalMonths = years * 12;
  var principalPerMonth = totalAmount / totalMonths;
  var totalInterest = 0;
  
  var monthlyPayments = [];
  for (var i = 0; i < totalMonths; i++) {
    var interest = (totalAmount - i * principalPerMonth) * monthlyRate;
    var monthlyPayment = principalPerMonth + interest;
    totalInterest += interest;
    
    monthlyPayments.push(monthlyPayment.toFixed(2));
  }
  
  var totalPayment = totalAmount + totalInterest;
  
  return {
    monthlyPayments: monthlyPayments,
    totalPayment: totalPayment.toFixed(2),
    totalInterest: totalInterest.toFixed(2)
  };
}

使用这些函数，你可以在网页上创建一个表单，让用户输入房贷金额、贷款期限和利率，并根据用户选择的计算方式（等额本息或等额本金）计算月供、总还款额和利息。