等额本息

const result = equalInstallmentRecursive(400000, 120,0.035, );
   function equalInstallmentRecursive(amount, term, annualRate) {
                const monthRate = annualRate / 12;
                const total =
                  (amount * monthRate * Math.pow(1 + monthRate, term)) /
                  (Math.pow(1 + monthRate, term) - 1);
                const details = [];
  
	// 递归主体
	function build(balance, leftTerm, period) {
	  if (leftTerm <= 0 || balance <= 0) return;
  
	  const interestRaw = balance * monthRate;
	  const interest = +interestRaw.toFixed(2);
	  const fixedPayment = +total.toFixed(2);
	  const fixedPrincipal = +(fixedPayment - interest).toFixed(2);
  
	  details.push({
		period,
		principal: fixedPrincipal,
		interest: interest,
		total: fixedPayment,
	  });
  
	  const nextBalance = +(balance - fixedPrincipal).toFixed(2);
	  build(nextBalance, leftTerm - 1, period + 1);
	}
  
	build(amount, term, 1);
	return { details };
  }