Angular create Class and objects

import { Component, Input } from "@angular/core";

class Model {
    param1: string;
}

@Component({
    selector: "testWidget",
    template: "<div>This is a test and {{model.param1}} is my param.</div>",
    providers: [Model]
})

export class testWidget {
    constructor(private model: Model) {}
}

another Ways of create class

 export class Model {

    param1: string;
}

Import { Model } from './model';

Initialize in the component:
export class testWidget {
   public model: Model;
   constructor(){
       this.model = new Model();
       this.model.param1 = "your string value here";
   }
}

Access it appropriately in the html:
@Component({
      selector: "testWidget",
      template: "<div>This is a test and {{model.param1}} is my param.</div>"
})
Simpal code class and object
   import { Component } from '@angular/core';

class model {
  username : string;
  password : string;
}

@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})



export class AppComponent {

 username : string;
 password : string;
  usermodel = new model();

  login(){
  if(this.usermodel.username == "admin"){
    alert("hi");
  }else{
    alert("bye");
    this.usermodel.username = "";
  }    
  }
}

and the html goes like this :
<div class="login">
  Usernmae : <input type="text" [(ngModel)]="usermodel.username"/>
  Password : <input type="text" [(ngModel)]="usermodel.password"/>
  <input type="button" value="Click Me" (click)="login()" />
</div>