“Event”类型的参数不能赋值给“string”类型的参数

在下面的代码中,我想使用eventemitters来调用方法“onlyNewAddItems”。

@Output() newItemValue = new EventEmitter<string>();

  addNewItem(val : string) {
    this.newItemValue.emit(val);
    console.log("add new item:" + val);
    this.items.push(val);
  }

为了绑定到这个事件,我做了以下操作:

<h1 (newItemValue) = onlyNewlyAddedItems($event)></h1>

但是当我编译代码时,我收到以下错误

Error: src/app/app.component.html:4:42 - error TS2345: Argument of type 'Event' is not assignable to parameter of type 'string'.

4 <h1 (newItemValue) = onlyNewlyAddedItems($event)></h1>                                        
  src/app/app.component.ts:5:16
    5   templateUrl: './app.component.html',
                     ~~~~~~~~~~~~~~~~~~~~~~
    Error occurs in the template of component AppComponent.
    

请让我知道如何通过eventemitter执行“onlyNewlyAddedItems”方法。

应用组件.component.ts

import { Component, Input, Output, EventEmitter } from '@angular/core';
@Component({
  selector: 'app-root',
  templateUrl: './app.component.html',
  styleUrls: ['./app.component.css']
})
export class AppComponent {
  title = 'InputOutputBindings';
  currentItem = 'TV';
  items = ['item1', 'item2', 'item3', 'item4'];

  @Output() newItemValue = new EventEmitter<string>();

  addNewItem(val : string) {
    this.newItemValue.emit(val);
    console.log("add new item:" + val);
    this.items.push(val);
  }

  onlyNewlyAddedItems(val : string) {
    console.log("onlyNewlyAddedItems:" + val);
  }
}

应用程序组件.html :

<h1 #test = customdirective appItemDetails [item]="currentItem">{{currentItem}}  item</h1>
<label>Add an item: <input #newItem></label>
<button (click) = addNewItem(newItem.value)>add new item</button>
<h1 (newItemValue) = onlyNewlyAddedItems($event)></h1>