wxmini/utils/calcute.js

var calcute = {
  //商贷-公积金贷款统一函数
  singleDk: function(type, num, year, lilv) {
    var _this = this;
    // type:1等额本息 2等额本金，num 贷款金额 year贷款年限，lilv：贷款基准利率
    if (type == 1) {
      return _this.benxi(type, num, year, lilv)
    } else if (type == 2) {
      return _this.benjin(type, num, year, lilv)
    }
  },
  //组合贷款计算
  zuhe: function(type, sdnum, gjjnum, sdyear, gjjyear, sdlilv, gjjlilv) {
    var _this = this,
      year = sdyear > gjjyear ? sdyear : gjjyear;
    if (type == 1) {
      var sdObj = _this.benxi(type, sdnum, sdyear, sdlilv);
      var gjjObj = _this.benxi(type, gjjnum, gjjyear, gjjlilv);
      if (sdObj.monthdataArray.length > gjjObj.monthdataArray.length) {
        var mergemonthdataArray = sdObj.monthdataArray.map(function(item, index) {
          if (index < gjjObj.monthdataArray.length) {
            return {
              monthName: item.monthName,
              yuelixi: item.yuelixi + gjjObj.monthdataArray[index].yuelixi,
              yuebenjin: item.yuebenjin + gjjObj.monthdataArray[index].yuebenjin,
              leftFund: item.leftFund + gjjObj.monthdataArray[index].leftFund
            }
          } else {
            return {
              monthName: item.monthName,
              yuelixi: item.yuelixi,
              yuebenjin: item.yuebenjin,
              leftFund: item.leftFund
            }
          }
        })
      } else {
        var mergemonthdataArray = gjjObj.monthdataArray.map(function(item, index) {
          if (index < sdObj.monthdataArray.length) {
            return {
              monthName: item.monthName,
              yuelixi: item.yuelixi + sdObj.monthdataArray[index].yuelixi,
              yuebenjin: item.yuebenjin + sdObj.monthdataArray[index].yuebenjin,
              leftFund: item.leftFund + sdObj.monthdataArray[index].leftFund
            }
          } else {
            return {
              monthName: item.monthName,
              yuelixi: item.yuelixi,
              yuebenjin: item.yuebenjin,
              leftFund: item.leftFund
            }
          }
        })
      }
      return {
        yuegong: sdObj.yuegong + gjjObj.yuegong,
        totalLixi: sdObj.totalLixi + gjjObj.totalLixi,
        totalPrice: sdObj.totalPrice + gjjObj.totalPrice,
        monthdataArray: mergemonthdataArray,
        totalDknum: parseFloat(sdObj.totalDknum) + parseFloat(gjjObj.totalDknum),
        year: year
      }
    } else if (type == 2) {
      var sdObj = _this.benjin(type, sdnum, sdyear, sdlilv);
      var gjjObj = _this.benjin(type, gjjnum, gjjyear, gjjlilv);
      if (sdObj.monthdataArray.length > gjjObj.monthdataArray.length) {
        var mergemonthdataArray = sdObj.monthdataArray.map(function(item, index) {
          if (index < gjjObj.monthdataArray.length) {
            return {
              monthName: item.monthName,
              yuelixi: item.yuelixi + gjjObj.monthdataArray[index].yuelixi,
              yuebenjin: item.yuebenjin + gjjObj.monthdataArray[index].yuebenjin,
              leftFund: item.leftFund + gjjObj.monthdataArray[index].leftFund
            }
          } else {
            return {
              monthName: item.monthName,
              yuelixi: item.yuelixi,
              yuebenjin: item.yuebenjin,
              leftFund: item.leftFund
            }
          }
        })
      } else {
        var mergemonthdataArray = gjjObj.monthdataArray.map(function(item, index) {
          if (index < sdObj.monthdataArray.length) {
            return {
              monthName: item.monthName,
              yuelixi: item.yuelixi + sdObj.monthdataArray[index].yuelixi,
              yuebenjin: item.yuebenjin + sdObj.monthdataArray[index].yuebenjin,
              leftFund: item.leftFund + sdObj.monthdataArray[index].leftFund
            }
          } else {
            return {
              monthName: item.monthName,
              yuelixi: item.yuelixi,
              yuebenjin: item.yuebenjin,
              leftFund: item.leftFund
            }
          }
        })
      }
      return {
        yuegong: sdObj.yuegong + gjjObj.yuegong,
        totalLixi: sdObj.totalLixi + gjjObj.totalLixi,
        totalPrice: sdObj.totalPrice + gjjObj.totalPrice,
        yuegongdijian: sdObj.yuegongdijian + gjjObj.yuegongdijian,
        totalDknum: parseFloat(sdObj.totalDknum) + parseFloat(gjjObj.totalDknum),
        year: year,
        monthdataArray: mergemonthdataArray
      }
    }
  },
  //等额本息计算
  benxi: function(type, num, year, lilv) {
    //每月月供额=〔贷款本金×月利率×(1＋月利率)＾还款月数〕÷〔(1＋月利率)＾还款月数-1〕
    var month = parseInt(year) * 12,
      monthlilv = parseFloat(lilv) / 12,
      dknum = parseFloat(num) * 10000;
    //每月月供
    var yuegong = (dknum * monthlilv * Math.pow((1 + monthlilv), month)) / (Math.pow((1 + monthlilv), month) - 1);
    //总利息=还款月数×每月月供额-贷款本金
    var totalLixi = month * yuegong - dknum;
    //还款总额 总利息+贷款本金
    var totalPrice = totalLixi + dknum,
      leftFund = totalLixi + dknum;
    //循环月份
    var monthdataArray = [],
      nowmonth = new Date().getMonth(),
      realmonth = 0;
    for (var i = 1; i <= month; i++) {
      realmonth = nowmonth + i;
      var yearlist = Math.floor(i / 12);
      realmonth = realmonth - 12 * yearlist;
      if (realmonth > 12) {
        realmonth = realmonth - 12
      }
      //console.log(realmonth)
      //每月应还利息=贷款本金×月利率×〔(1+月利率)^还款月数-(1+月利率)^(还款月序号-1)〕÷〔(1+月利率)^还款月数-1〕
      var yuelixi = dknum * monthlilv * (Math.pow((1 + monthlilv), month) - Math.pow((1 + monthlilv), i - 1)) / (Math.pow((1 + monthlilv), month) - 1);
      //每月应还本金=贷款本金×月利率×(1+月利率)^(还款月序号-1)÷〔(1+月利率)^还款月数-1〕
      var yuebenjin = dknum * monthlilv * Math.pow((1 + monthlilv), i - 1) / (Math.pow((1 + monthlilv), month) - 1);
      leftFund = leftFund - (yuelixi + yuebenjin);
      if (leftFund < 0) {
        leftFund = 0
      }
      monthdataArray[i - 1] = {
        monthName: realmonth + "月",
        yuelixi: yuelixi,
        yuebenjin: yuebenjin,
        //剩余还款
        leftFund: leftFund
      }
    }
    return {
      yuegong: yuegong,
      totalLixi: totalLixi,
      totalPrice: totalPrice,
      monthdataArray: monthdataArray,
      totalDknum: num,
      year: year
    };
  },
  //等额本金计算
  benjin: function(type, num, year, lilv) {
    var month = parseInt(year) * 12,
      monthlilv = parseFloat(lilv) / 12,
      dknum = parseFloat(num) * 10000,
      yhbenjin = 0; //首月还款已还本金金额是0
    //每月应还本金=贷款本金÷还款月数
    var everymonthyh = dknum / month
    //每月月供额=(贷款本金÷还款月数)+(贷款本金-已归还本金累计额)×月利率
    var yuegong = everymonthyh + (dknum - yhbenjin) * monthlilv;
    //每月月供递减额=每月应还本金×月利率=贷款本金÷还款月数×月利率
    var yuegongdijian = everymonthyh * monthlilv;
    //总利息=〔(总贷款额÷还款月数+总贷款额×月利率)+总贷款额÷还款月数×(1+月利率)〕÷2×还款月数-总贷款额
    var totalLixi = ((everymonthyh + dknum * monthlilv) + dknum / month * (1 + monthlilv)) / 2 * month - dknum;
    //还款总额 总利息+贷款本金
    var totalPrice = totalLixi + dknum,
      leftFund = totalLixi + dknum;
    //循环月份
    var monthdataArray = [],
      nowmonth = new Date().getMonth(),
      realmonth = 0;
    for (var i = 1; i <= month; i++) {
      realmonth = nowmonth + i;
      var yearlist = Math.floor(i / 12);
      realmonth = realmonth - 12 * yearlist;
      if (realmonth > 12) {
        realmonth = realmonth - 12
      }
      yhbenjin = everymonthyh * (i - 1);
      var yuebenjin = everymonthyh + (dknum - yhbenjin) * monthlilv;
      //每月应还利息=剩余本金×月利率=(贷款本金-已归还本金累计额)×月利率
      var yuelixi = (dknum - yhbenjin) * monthlilv;
      leftFund = leftFund - yuebenjin;
      if (leftFund < 0) {
        leftFund = 0
      }
      monthdataArray[i - 1] = {
        monthName: realmonth + "月",
        yuelixi: yuelixi,
        //每月本金
        yuebenjin: everymonthyh,
        //剩余还款
        leftFund: leftFund
      }
    }
    return {
      yuegong: yuegong,
      totalLixi: totalLixi,
      totalPrice: totalPrice,
      yuegongdijian: yuegongdijian,
      monthdataArray: monthdataArray,
      totalDknum: num,
      year: year
    }
  }
}

module.exports = {
  calcute: calcute
}