有时候，提出正确的问题会有所帮助：d
这是代码。以防有人在谷歌上也找不到它。
html文件：

<input 
    (keyup.enter)="createPost(title)" #title
    type="text" class="form-control">
<ul class="list-group">
    <li 
    *ngFor="let post of posts"
    class="list-group-item">
    {{ post.title }}
    </li>
</ul>

ts文件：

import { Component, OnInit, Input } from '@angular/core';
import { HttpClient } from "@angular/common/http";

@Component({
  selector: 'post',
  templateUrl: './post.component.html',
  styleUrls: ['./post.component.css']
})
export class PostComponent  {
  posts: any;
  private url=`http://jsonplaceholder.typicode.com/posts`;

  constructor(private httpClient: HttpClient) { 
    httpClient.get(this.url)
      .subscribe(response => {
        this.posts = response;
      }); 
  }

  createPost(input: HTMLInputElement) {
    let post: any = { title: input.value };
    this.httpClient.post(this.url, JSON.stringify(post))
      .subscribe((response:any) => {
        post['id'] = response.id;
        this.posts.splice(0, 0, post);
        console.log(post['id']);
    });
  }

}