Angular4實現動態添加刪除表單輸入框功能

<h5>動態添加表單</h5> 
<div class="form"> 
 <div class="form-group form-group-sm" *ngFor="let i of login"> 
 <label class="col-form-label">用戶名</label> 
 <input class="form-control" [(ngModel)]="i.username" value="{{i.username}}"> 
 <label class="col-form-label">密碼</label> 
 <input class="form-control" [(ngModel)]="i.password" value="{{i.password}}"> 
 <button class="btn btn-link" (click)="removeInput(i)">刪除</button> 
 </div> 
 <button (click)="addInput()">增加</button> 
 <button (dblclick)="dbclick()">雙擊</button> 
 {{ login | json }} 
</div> 

username: any; 
 id: number = 1; 
 login:any = [{"username": "username" + this.id,"password": "pwd" + this.id}]; 
 addInput() { 
 console.log('點擊'); 
 console.log(this.login); 
 let number = this.login.length + 1; 
 this.login.push({"username": "username" + number, "password": "pwd" + number}); 
 console.log(this.login); 
 } 
 removeInput(item) { 
 console.log(item); 
 let i = this.login.indexOf(item); 
 console.log(i); 
 this.login.splice(i, 1); 
 }