FormArray：无法读取打字稿中未定义的属性“ push”

Question

错误TypeError：无法读取未定义的属性“ push”

addAddress() {
    const control = <FormArray>this.AddUserstep2Form.controls['addresses'];  

    const addrCtrl = this.initAddress();

    control.push(addrCtrl);

  }
initAddress() {
    return this.fb.group({
      stateCode: [''],
      cityId: ['']
    }); 
  }

Answer 1

这是当control为null时发生的，您需要使用空数组进行初始化

const control = <FormArray>this.AddUserstep2Form.controls['addresses'];  
const addrCtrl = this.initAddress();
if(control && control.length > 0){
 control.push(addrCtrl);
}else
{
 control = [];
 control.push(addrCtrl);
}