最近使用uniapp开发了个房贷计算器小程序，感觉uniapp对于开发小程序来说还是非常不错的，目前适配了微信小程序、qq小程序和支付宝小程序，由于抖音小程序和百度小程序目前不支持个人开发，暂时还没调试。
首先上几个截图：
其实这个小程序页面并不复杂，主要是各种计算公式，下面分享一下用到的公式：
1.等额本息公式：
// 等额本息计算方法
computedBX(total, rate, mouths) {
// 等额本息 每月还本付息金额=[贷款本金×月利率×(1+月利率)^还款月数]÷[(1+月利率)^还款月数-1]
// 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〕
// 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〕
// 总利息=还款月数×每月月供额-贷款本金
let result = (total * rate * Math.pow(1 + rate, mouths)) / (Math.pow(1 + rate, mouths) - 1)
// result = result.toFixed(2)
let total_rate = result.toFixed(2) * mouths
let list = []
for (let i = 1; i <= mouths; i++) {
//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〕
let mybj = (total * rate * Math.pow(1 + rate, i - 1) / (Math.pow(1 + rate, mouths) - 1)).toFixed(2)
//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〕
let mylx = (total * rate * (Math.pow(1 + rate, mouths) - Math.pow(1 + rate, i - 1)) / (Math.pow(1 + rate, mouths) - 1)).toFixed(2)
list.push({
res: Number( result.toFixed(2) ),
yu: Number( (total_rate - result.toFixed(2) * i).toFixed(2) ),
mybj:mybj,
mylx:mylx
})
}
// 总利息
let total_lixi = Number( (mouths * result - total).toFixed(2) )
// 总利息 + 贷款本金
let total_er = Number( (Number(total_lixi) + Number(total)).toFixed(2) )
return {
result: Number( result.toFixed(2) ),
total_lixi,
total_er,
list,
total,
dijian: 0
}
}2.等额本金计算公式：
// 等额本金计算方法
// 贷款本金 月利率 还款月数
computedBJ(total, rate, mouths) {
// 等额本金的计算公式为： 每月还本付息金额=（本金/还款月数）+（本金－累计已还本金）×月利率
// 每月应还本金=贷款本金÷还款月数
// 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。
// 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
// 总利息=（还款月数+1）×贷款总额×月利率÷2
// 月供
let res
// 已还本金
let yhbj = 0;
// 已还的本息
let yhbx = 0
// 递减金额
let dijian
res = (total / mouths) + (total - yhbj) * rate
res = res.toFixed(2)
yhbx = res + yhbx
let result = Number(res)
let total_lixi = (mouths + 1) * total * rate / 2
let total_er = total_lixi + total
let list = []
//每月本金 每月归还本金=贷款总额÷归还月数；
let mybj = (total / mouths).toFixed(2)
//每月利息 、每月还款利息=(贷款总额-累计已还本金)×月利率；
let mylx = (total * rate).toFixed(2)
list.push({
res: res,
yu: (total_er - yhbx).toFixed(2),
mybj:mybj,
mylx:mylx
})
dijian = Number((total / mouths * rate).toFixed(2))
for (let i = 1; i < mouths; i++) {
yhbj = total / mouths * i
res = (total / mouths) + (total - yhbj) * rate
res = res.toFixed(2)
yhbx = Number(res) + Number(yhbx)
mylx = ((total - mybj * i) * rate).toFixed(2)
list.push({
res: res,
yu: Number( (total_er - yhbx).toFixed(2) ),
mybj:mybj,
mylx:mylx
})
}
return {
result,
total_lixi,
total_er,
list,
total,
dijian
}
}3.提前还贷所有逻辑代码：文章来源：https://www.toymoban.com/news/detail-665832.html
//一次性提前还款计算（等额本息）
calculateEqualPrincipalAndInterest(){
let principal = this.datas.ydkze * 10000
let monthRate = this.datas.yfdlv / (100 * 12);//月利率
let months = this.datas.ydkqx * 12
let payTimes = this.monthsBetw(this.datas.schkrq,this.datas.tqhkrq)
let preLoan = (principal * monthRate * Math.pow((1 + monthRate), months)) / (Math.pow((1 + monthRate), months) - 1);//每月还款金额
let totalMoney = preLoan * months;//还款总额
let interest = totalMoney - principal;//还款总利息
let leftLoan = principal * Math.pow(1 + monthRate, payTimes) - preLoan * (Math.pow(1 + monthRate, payTimes) - 1) / monthRate;//n个月后欠银行的钱
this.payLoan = principal - leftLoan;//已还本金
this.payTotal = preLoan * payTimes;//已还总金额
this.payInterest = this.payTotal - this.payLoan;//已还利息
this.totalPayAhead = leftLoan * (1 + monthRate);//剩余一次还清
this.saveInterest = totalMoney - this.payTotal - this.totalPayAhead;节省利息
this.principal = principal
this.interest = interest
this.totalMoney = totalMoney
this.payTimes = payTimes
this.preLoan = preLoan
this.leftMonth = 0
this.leftLoan = leftLoan//剩余还款本金
},
//一次性提前还款计算(等额本金)
calculateEqualPrincipal(){
let principal = this.datas.ydkze * 10000
let monthRate = this.datas.yfdlv / (100 * 12);//月利率
let months = this.datas.ydkqx * 12
let payTimes = this.monthsBetw(this.datas.schkrq,this.datas.tqhkrq)
let prePrincipal = principal / months;//每月还款本金
let firstMonth = prePrincipal + principal * monthRate;//第一个月还款金额
let decreaseMonth = prePrincipal * monthRate;//每月利息递减
let interest = (months + 1) * principal * monthRate / 2;//还款总利息
let totalMoney = principal + interest;//还款总额
this.payLoan = prePrincipal * payTimes;//已还本金
this.leftLoan = principal - this.payLoan//剩余还款本金
this.payInterest = (principal * payTimes - prePrincipal * (payTimes - 1) * payTimes / 2) * monthRate;//已还利息
this.payTotal = this.payLoan + this.payInterest;//已还总额
this.totalPayAhead = (principal - this.payLoan) * (1 + monthRate);//提前还款金额（剩余本金加上剩余本金当月利息）
this.saveInterest = totalMoney - this.payTotal - this.totalPayAhead;//节省利息
this.principal = principal
this.interest = interest
this.totalMoney = totalMoney
this.payTimes = payTimes
this.prePrincipal = prePrincipal
this.firstMonth = firstMonth
this.decreaseMonth = decreaseMonth
this.leftMonth = 0
},
//部分提前还款计算（等额本息、月供不变）
calculateEqualPrincipalAndInterestApart(){
let principal = this.datas.ydkze * 10000
let monthRate = this.datas.yfdlv / (100 * 12);//月利率
let months = this.datas.ydkqx * 12
let payTimes = this.monthsBetw(this.datas.schkrq,this.datas.tqhkrq)
let aheadPrincipalTotal = this.datas.tqhkje * 10000
let preLoan = (principal * monthRate * Math.pow((1 + monthRate), months)) / (Math.pow((1 + monthRate), months) - 1);//每月还款金额
let totalMoney = preLoan * months;//还款总额
let interest = totalMoney - principal;//还款总利息
let leftLoanBefore = principal * Math.pow(1 + monthRate, payTimes) - preLoan * (Math.pow(1 + monthRate, payTimes) - 1) / monthRate;//提前还款前欠银行的钱
//提前还房贷的利息计算公式为：剩余贷款本金×[(提前还款日-上次扣款日)的天数]×日利率(日利率=年利率÷360)
let lx = leftLoanBefore * this.datas.yfdlv / (100 * 360) * this.dayCha(this.datas.schkrq,this.datas.tqhkrq)
let aheadPrincipal = aheadPrincipalTotal - lx
// let leftLoan = principal * Math.pow(1 + monthRate, payTimes + 1) - preLoan * (Math.pow(1 + monthRate, payTimes + 1) - 1) / monthRate - aheadPrincipal;//提前还款后欠银行的钱
let leftLoan = leftLoanBefore - aheadPrincipal;
let payLoan = principal - leftLoanBefore;//已还本金
let payTotal = preLoan * payTimes;//已还总金额
let payInterest = payTotal - payLoan;//已还利息
// let aheadTotalMoney = aheadPrincipal + preLoan;//提前还款总额
let aheadTotalMoney = aheadPrincipal
//计算剩余还款期限
let leftMonth = Math.floor(Math.log(preLoan / (preLoan - leftLoan * monthRate)) / Math.log(1 + monthRate));
let newPreLoan = (leftLoan * monthRate * Math.pow((1 + monthRate), leftMonth)) / (Math.pow((1 + monthRate), leftMonth) - 1);//剩余贷款每月还款金额
let leftTotalMoney = newPreLoan * leftMonth;//剩余还款总额
// let leftInterest = leftTotalMoney - (leftLoan - aheadPrincipal);//剩余还款总利息
let leftInterest = leftTotalMoney - leftLoan
this.saveInterest = totalMoney - aheadTotalMoney - leftTotalMoney - payTotal;//节省利息
this.principal = principal
this.interest = interest
this.totalMoney = totalMoney
this.payTotal = payTotal
this.payLoan = payLoan
this.payInterest = payInterest
this.payTimes = payTimes
this.leftTotalMoney = leftTotalMoney
this.leftInterest = leftInterest
this.aheadPrincipal = aheadPrincipal
this.newPreLoan = newPreLoan
this.preLoan = preLoan
this.leftMonth = leftMonth
this.leftTotalMoney = leftTotalMoney
this.leftInterest = leftInterest
this.leftLoan = leftLoan
this.aheadPrincipalTotal = aheadPrincipalTotal
this.lx = lx
},
//部分提前还款计算(等额本金、月供不变)
calculateEqualPrincipalApart(){
let principal = this.datas.ydkze * 10000
let monthRate = this.datas.yfdlv / (100 * 12);//月利率
let months = this.datas.ydkqx * 12
let payTimes = this.monthsBetw(this.datas.schkrq,this.datas.tqhkrq)
let aheadPrincipalTotal = this.datas.tqhkje * 10000
let prePrincipal = principal / months;//每月还款本金
let firstMonth = prePrincipal + principal * monthRate;//第一个月还款金额
let decreaseMonth = prePrincipal * monthRate;//每月利息递减
let interest = (months + 1) * principal * monthRate / 2;//还款总利息
let totalMoney = principal + interest;//还款总额
let payLoan = prePrincipal * payTimes;//已还本金
let payInterest = (principal * payTimes - prePrincipal * (payTimes - 1) * payTimes / 2) * monthRate;//已还利息
let payTotal = payLoan + payInterest;//已还总额
//提前还房贷的利息计算公式为：剩余贷款本金×[(提前还款日-上次扣款日)的天数]×日利率(日利率=年利率÷360)
let lx = (principal - payLoan) * this.datas.yfdlv / (100 * 360) * this.dayCha(this.datas.schkrq,this.datas.tqhkrq)
let aheadPrincipal = aheadPrincipalTotal - lx
// let aheadTotalMoney = (principal - payLoan) * monthRate + aheadPrincipal + prePrincipal;//提前还款金额
let aheadTotalMoney = aheadPrincipal;
// let leftLoan = principal - aheadPrincipal - payLoan - prePrincipal;//剩余金额
let leftLoan = principal - aheadPrincipal - payLoan;
let leftMonth = Math.floor(leftLoan / prePrincipal);剩余还款期限
let newPrePrincipal = leftLoan / leftMonth;//新的每月还款本金
let newFirstMonth = newPrePrincipal + leftLoan * monthRate;//新的第一个月还款金额
let newDecreaseMonth = newPrePrincipal * monthRate;//新的每月利息递减
let leftInterest = (leftMonth + 1) * leftLoan * monthRate / 2;//还款总利息
let leftTotalMoney = leftLoan + leftInterest;//剩余还款总额
this.saveInterest = totalMoney - payTotal - aheadTotalMoney - leftTotalMoney;//节省利息
this.principal = principal
this.interest = interest
this.totalMoney = totalMoney
this.payTotal = payTotal
this.payLoan = payLoan
this.payInterest = payInterest
this.payTimes = payTimes
this.leftTotalMoney = leftTotalMoney
this.leftLoan = leftLoan
this.leftInterest = leftInterest
this.aheadPrincipal = aheadPrincipal
this.newPrePrincipal = newPrePrincipal
this.newFirstMonth = newFirstMonth
this.newDecreaseMonth = newDecreaseMonth
this.prePrincipal = prePrincipal
this.firstMonth = firstMonth
this.decreaseMonth = decreaseMonth
this.leftMonth = leftMonth
this.aheadPrincipalTotal = aheadPrincipalTotal
this.lx = lx
},
//部分提前还款计算（等额本息、期限不变）
calculateEqualPrincipalAndInterestApart2(){
let principal = this.datas.ydkze * 10000
let monthRate = this.datas.yfdlv / (100 * 12);//月利率
let months = this.datas.ydkqx * 12
let payTimes = this.monthsBetw(this.datas.schkrq,this.datas.tqhkrq)
let aheadPrincipalTotal = this.datas.tqhkje * 10000
let leftMonth = months - payTimes;//剩余还款期限
let preLoan = (principal * monthRate * Math.pow((1 + monthRate), months)) / (Math.pow((1 + monthRate), months) - 1);//每月还款金额
let totalMoney = preLoan * months;//还款总额
let interest = totalMoney - principal;//还款总利息
let leftLoanBefore = principal * Math.pow(1 + monthRate, payTimes) - preLoan * (Math.pow(1 + monthRate, payTimes) - 1) / monthRate;//提前还款前欠银行的钱
// let leftLoan = principal * Math.pow(1 + monthRate, payTimes + 1) - preLoan * (Math.pow(1 + monthRate, payTimes + 1) - 1) / monthRate;//提前还款后银行的钱
//提前还房贷的利息计算公式为：剩余贷款本金×[(提前还款日-上次扣款日)的天数]×日利率(日利率=年利率÷360)
let lx = leftLoanBefore * this.datas.yfdlv / (100 * 360) * this.dayCha(this.datas.schkrq,this.datas.tqhkrq)
let aheadPrincipal = aheadPrincipalTotal - lx
let leftLoan = leftLoanBefore - aheadPrincipal
let payLoan = principal - leftLoanBefore;//已还本金
let payTotal = preLoan * payTimes;//已还总金额
let payInterest = payTotal - payLoan;//已还利息
// let aheadTotalMoney = preLoan + aheadPrincipal;//下个月还款金额
let aheadTotalMoney = aheadPrincipal;
let newPreLoan = ((leftLoan) * monthRate * Math.pow((1 + monthRate), months - payTimes - 1)) / (Math.pow((1 + monthRate), months - payTimes - 1) - 1);//下个月起每月还款金额
let leftTotalMoney = newPreLoan * (months - payTimes);//剩余还款总额
// let leftInterest = leftTotalMoney - (leftLoan - aheadPrincipal);//剩余还款总利息
let leftInterest = leftTotalMoney - leftLoan
this.saveInterest = totalMoney - payTotal - aheadTotalMoney - leftTotalMoney;//节省利息
this.principal = principal
this.interest = interest
this.totalMoney = totalMoney
this.payTotal = payTotal
this.payLoan = payLoan
this.payInterest = payInterest
this.payTimes = payTimes
this.leftTotalMoney = leftTotalMoney
this.leftLoan = leftLoan
this.leftInterest = leftInterest
this.aheadPrincipal = aheadPrincipal
this.newPreLoan = newPreLoan
this.preLoan = preLoan
this.leftMonth = leftMonth
this.aheadPrincipalTotal = aheadPrincipalTotal
this.lx = lx
},
//部分提前还款计算(等额本金、期限不变)
calculateEqualPrincipalApart2(){
let principal = this.datas.ydkze * 10000
let monthRate = this.datas.yfdlv / (100 * 12);//月利率
let months = this.datas.ydkqx * 12
let payTimes = this.monthsBetw(this.datas.schkrq,this.datas.tqhkrq)
let aheadPrincipalTotal = this.datas.tqhkje * 10000
let prePrincipal = principal / months;//每月还款本金
let firstMonth = prePrincipal + principal * monthRate;//第一个月还款金额
let decreaseMonth = prePrincipal * monthRate;//每月利息递减
let interest = (months + 1) * principal * monthRate / 2;//还款总利息
let totalMoney = principal + interest;//还款总额
let payLoan = prePrincipal * payTimes;//已还本金
let payInterest = (principal * payTimes - prePrincipal * (payTimes - 1) * payTimes / 2) * monthRate;//已还利息
let payTotal = payLoan + payInterest;//已还总额
//提前还房贷的利息计算公式为：剩余贷款本金×[(提前还款日-上次扣款日)的天数]×日利率(日利率=年利率÷360)
let lx = (principal - payLoan) * this.datas.yfdlv / (100 * 360) * this.dayCha(this.datas.schkrq,this.datas.tqhkrq)
let aheadPrincipal = aheadPrincipalTotal - lx
// let aheadTotalMoney = (principal - payLoan) * monthRate + aheadPrincipal + prePrincipal;//提前还款金额
let aheadTotalMoney = aheadPrincipal;
let leftMonth = months - payTimes;//剩余还款期限
// let leftLoan = principal - aheadPrincipal - payLoan - prePrincipal;
let leftLoan = principal - aheadPrincipal - payLoan;
let newPrePrincipal = leftLoan / leftMonth;//新的每月还款本金
let newFirstMonth = newPrePrincipal + leftLoan * monthRate;//新的第一个月还款金额
let newDecreaseMonth = newPrePrincipal * monthRate;//新的每月利息递减
let leftInterest = (leftMonth + 1) * leftLoan * monthRate / 2;//还款总利息
let leftTotalMoney = leftLoan + leftInterest;//剩余还款总额
this.saveInterest = totalMoney - payTotal - aheadTotalMoney - leftTotalMoney;节省利息
this.principal = principal
this.interest = interest
this.totalMoney = totalMoney
this.payTotal = payTotal
this.payLoan = payLoan
this.payInterest = payInterest
this.payTimes = payTimes
this.leftTotalMoney = leftTotalMoney
this.leftLoan = leftLoan
this.leftInterest = leftInterest
this.aheadPrincipal = aheadPrincipal
this.newPrePrincipal = newPrePrincipal
this.newFirstMonth = newFirstMonth
this.newDecreaseMonth = newDecreaseMonth
this.prePrincipal = prePrincipal
this.firstMonth = firstMonth
this.decreaseMonth = decreaseMonth
this.leftMonth = leftMonth
this.aheadPrincipalTotal = aheadPrincipalTotal
this.lx = lx
}最后附上我的微信小程序，由于不能放二维码，大家可以去微信搜一下，名字叫做：房贷计算器工具文章来源地址https://www.toymoban.com/news/detail-665832.html
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