如何在使用Angular6+将记录插入数组期间防止重复值

**PARENTCOMPONENT.HTML:**
<div class="form-group" style="margin-left:30px;margin-top:30px;">
    <input type="text" class="form-control" placeholder="Posts" name="post" [(ngModel)]="post" #clearText>
</div>

<button type="submit" class="btn btn-sm btn-primary" (click)="AddServer(post)" 
style="margin-left:30px;margin-top:10px;" (blur) = "clearText.value = ''">Click</button>

<app-child [childPost]="parentPosts"></app-child>


**PARENTCOMPONENT.TS:**
import { Component, OnInit } from '@angular/core';

@Component({
  selector: 'app-parent',
  templateUrl: './parent.component.html',
  styleUrls: ['./parent.component.css']
})
export class ParentComponent implements OnInit {

post = '';
parentPosts: any[] = [];

  constructor() { }

  ngOnInit() {
  }

  AddServer(post)
  {
    this.parentPosts.push(post);
    console.log(post);
  }
}

**CHILDCOMPONENT.HTML:**
<div style="margin-left: 30px; margin-top:10px;" *ngFor="let p of childPost">
  <p>{{p}}</p>
</div>

**CHILDCOMPONENT.TS:**
import { Component, OnInit, Input } from '@angular/core';

@Component({
  selector: 'app-child',
  templateUrl: './child.component.html',
  styleUrls: ['./child.component.css']
})
export class ChildComponent implements OnInit {

@Input() childPost: any[] = [];
  constructor() { }

  ngOnInit() {
  }

}

嗨，伙计们，上面代码是用文本框值和parencomponent中的按钮将数据从父组件插入到子组件。TS代码我需要的是在将值推入数组的过程中，值必须是唯一的，如果我发布重复的值，它会抛出一个警告或错误消息，值已经这样插入了，所以请帮助我解决这个问题。。。。