观察HttpClient.post()请求中的事件如何获取响应头内容长度？- Angular Http客户端

import { HttpClient } from '@angular/common/http';

constructor(private http: HttpClient) {}

sendPostRequest() {
  const url = 'https://example.com/api/endpoint';
  const body = { key: 'value' };

  this.http.post(url, body, { observe: 'response' }).subscribe(
    (response) => {
      const contentLength = response.headers.get('Content-Length');
      console.log('Content Length:', contentLength);
    },
    (error) => {
      console.error('Error:', error);
    }
  );
}