Typescript 移除（i）角度5格式阵列的问题

在我运行这个方法之后

const control = <FormArray>this.proposalForm.get('proposals');
control.removeAt(i);

当我尝试运行ComputeBalance时，ValueChanges返回null，因为控件现在为null

请问，当我运行AddMorePropositions（）动态添加更多表单时，如何取消对已删除控件的注册，使其再次可用

---

感谢

以下是如何声明和销毁订阅：

x: any;
mySub: Subscription;

ngOnInit() {
  this.mySub.subscribe(val => this.x = val); 
}

ngOnDestroy() {
  this.mySub.unsubscribe();
}

根据您的描述，removeAt（i）发生在computeBalances（）之前。这会导致未定义的错误

要防止出现这种情况，请尝试在subscribe调用中调用removeAt：

this.proposalForm.get('proposals.' + this.count + '.ProposedAmount').valueChanges.subscribe(value => {
 if (this.count == 0) {
     this.details.CurrentBalance = this.originalBalance - value;
 } else {
     this.details.CurrentBalance = this.latestOutstandingBalance - value
 }
 //do the removeAt(i) here.
})

---

谢谢，我想这已经解决了。我把t

his.myFormValueChanges$ = this.proposalForm.controls['proposals'].valueChanges;
        this.myFormValueChanges$.subscribe(units => this.updateCalculations(units));

在我的ngOnInt（）中

然后我实现了如下更新计算

private updateCalculations(units: any) {
        const control = <FormArray>this.proposalForm.controls['proposals'];
        // console.log(units)
        for (let i in units) {
            if (units[i].ProposedAmount != '') {
                if (i == "0") {
                    this.details.CurrentBalance = this.originalBalance - units[i].ProposedAmount;
                }
                else {
                    this.details.CurrentBalance = this.latestOutstandingBalance - units[i].ProposedAmount;
                }
                this.latestOutstandingBalance = this.details.CurrentBalance;
            }



            const endDate = new Date(units[i].EndDate.year, units[i].EndDate.month - 1, units[i].EndDate.day);
            const startDate = new Date(units[i].StartDate.year, units[i].StartDate.month - 1, units[i].StartDate.day);
            let dateDiff = +endDate.getMonth() - +startDate.getMonth();
            let monthDifference = dateDiff + (12 * (endDate.getFullYear() - startDate.getFullYear()));
            let yearDifference = monthDifference / 12;

            if (units[i].PaymentPlan == 1) {
                control.at(+i).get('InstallmentAmount').setValue((units[i].ProposedAmount / (monthDifference / units[i].Frequency)).toFixed(2), { onlySelf: true, emitEvent: false })
            }

            else if (units[i].PaymentPlan == 2) {
                control.at(+i).get('InstallmentAmount').setValue(((units[i].ProposedAmount) / (monthDifference / (3 * units[i].Frequency))).toFixed(2), { onlySelf: true, emitEvent: false })

            }
            else if (units[i].PaymentPlan == 3) {
                control.at(+i).get('InstallmentAmount').setValue(((units[i].ProposedAmount) / (yearDifference / (2 * units[i].Frequency))).toFixed(2), { onlySelf: true, emitEvent: false })
            }

            else if (units[i].PaymentPlan == 4) {
                control.at(+i).get('InstallmentAmount').setValue(((units[i].ProposedAmount) / (yearDifference / units[i].Frequency)).toFixed(2), { onlySelf: true, emitEvent: false })

            }

            else {
                control.at(+i).get('InstallmentAmount').setValue((units[i].ProposedAmount / units[i].Frequency).toFixed(2), { onlySelf: true, emitEvent: false })

            }

        }

私有更新计算（单位：任意）{
const control=this.proposalForm.controls['proposals']；
//控制台日志（单位）
for（以单位表示）{
if（单位[i]。建议装载量！=''）{
如果（i==“0”）{
this.details.CurrentBalance=this.originalBalance-units[i]。建议安装量；
}
否则{
this.details.CurrentBalance=this.latestOutstandingBalance-单位[i]。建议安装量；
}
this.latestOutstandingBalance=this.details.CurrentBalance；
}
const endDate=新日期（单位[i].endDate.year，单位[i].endDate.month-1，单位[i].endDate.day）；
const startDate=新日期（单位[i]。startDate.year，单位[i]。startDate.month-1，单位[i]。startDate.day）；
让dateDiff=+endDate.getMonth（）-+startDate.getMonth（）；
让monthDifference=dateDiff+（12*（endDate.getFullYear（）-startDate.getFullYear（））；
设年差=月差/12；
if（单位[i]。付款计划==1）{
控件.at（+i）.get（'InstallmentAmount'）.setValue（（单位[i].ProposedAmount/（月差/units[i].Frequency））.toFixed（2），{仅限您自己：true，emitEvent:false}）
}
else if（单位[i]。付款计划==2）{
control.at（+i）.get（'InstallmentAmount'）.setValue（（（单位[i].ProposedAmount）/（月差/（3*单位[i].Frequency）））.toFixed（2），{onlySelf:true，emitEvent:false}）
}
else if（单位[i]。付款计划==3）{
control.at（+i）.get（'InstallmentAmount'）.setValue（（（单位[i].ProposedAmount）/（年差/（2*单位[i].Frequency））.toFixed（2），{仅自身：真，发射事件：假}）
}
else if（单位[i]。付款计划==4）{
control.at（+i）.get（'InstallmentAmount'）.setValue（（（单位[i].ProposedAmount）/（年差/单位[i].Frequency））.toFixed（2），{onlySelf:true，emitEvent:false}）
}
否则{
control.at（+i）.get（'InstallmentAmount'）.setValue（（单位[i].ProposedAmount/units[i].Frequency）.toFixed（2），{onlySelf:true，emitEvent:false}）
}
}

---

现在一切正常。感谢您的帮助

请查看我上面的回复。谢谢。我明白了。看起来.subscribe（value=>…中的值为空。您可以执行类似以下操作来取消订阅：

this.logsSub.UnSubscribe（）

但最好知道何时删除该控件。可能是在ComputeBalance（）之前先删除它。如果您还有其他问题和其他信息，请告诉我。您好，请问我应该取消订阅的this.logsAb是什么？我在运行AddMorePropositions（）时运行ComputeBalance（）添加另一个动态表单。如果我没有运行removeAt（i），一切都会好的。但一旦我运行removeAt（i），所有后续的AddMorePropositions（）将返回未定义的控件。我会假设您的proposalForm是订阅，因为您使用了.subscribe with它。

this.proposalForm.get（'Propositions.+this.count+'.ProposedAmount'）.valueChanges.subscribe

根据您的描述，removeAt（i）首先出现，这就是它导致未定义错误的原因。为了防止这种情况，请在.subscribe.this中执行removeProposalField（i:number）函数removeProposalFields（i:number）：void{const control=this.proposalForm.get（'proposals'）；let removedAmount=this.proposalForm.get（'proposals'）.value[i].ProposedAmount；this.latestOutstandingBalance=this.details.CurrentBalance+removedAmount；control.removeAt（i）；}你的意思是我应该把它放在一个亚脚本里吗？？

private updateCalculations(units: any) {
        const control = <FormArray>this.proposalForm.controls['proposals'];
        // console.log(units)
        for (let i in units) {
            if (units[i].ProposedAmount != '') {
                if (i == "0") {
                    this.details.CurrentBalance = this.originalBalance - units[i].ProposedAmount;
                }
                else {
                    this.details.CurrentBalance = this.latestOutstandingBalance - units[i].ProposedAmount;
                }
                this.latestOutstandingBalance = this.details.CurrentBalance;
            }



            const endDate = new Date(units[i].EndDate.year, units[i].EndDate.month - 1, units[i].EndDate.day);
            const startDate = new Date(units[i].StartDate.year, units[i].StartDate.month - 1, units[i].StartDate.day);
            let dateDiff = +endDate.getMonth() - +startDate.getMonth();
            let monthDifference = dateDiff + (12 * (endDate.getFullYear() - startDate.getFullYear()));
            let yearDifference = monthDifference / 12;

            if (units[i].PaymentPlan == 1) {
                control.at(+i).get('InstallmentAmount').setValue((units[i].ProposedAmount / (monthDifference / units[i].Frequency)).toFixed(2), { onlySelf: true, emitEvent: false })
            }

            else if (units[i].PaymentPlan == 2) {
                control.at(+i).get('InstallmentAmount').setValue(((units[i].ProposedAmount) / (monthDifference / (3 * units[i].Frequency))).toFixed(2), { onlySelf: true, emitEvent: false })

            }
            else if (units[i].PaymentPlan == 3) {
                control.at(+i).get('InstallmentAmount').setValue(((units[i].ProposedAmount) / (yearDifference / (2 * units[i].Frequency))).toFixed(2), { onlySelf: true, emitEvent: false })
            }

            else if (units[i].PaymentPlan == 4) {
                control.at(+i).get('InstallmentAmount').setValue(((units[i].ProposedAmount) / (yearDifference / units[i].Frequency)).toFixed(2), { onlySelf: true, emitEvent: false })

            }

            else {
                control.at(+i).get('InstallmentAmount').setValue((units[i].ProposedAmount / units[i].Frequency).toFixed(2), { onlySelf: true, emitEvent: false })

            }

        }