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

@Injectable()
export class MyService {
  constructor(private http: HttpClient) { }

  getData(param: string) {
    const url = `http://example.com/api/data?param=${param}`;
    return this.http.get(url);
  }
}

import { Component } from '@angular/core';
import { MyService } from './my.service';

@Component({
  selector: 'app-my-component',
  template: `
    Get Data
  `,
})
export class MyComponent {
  constructor(private myService: MyService) { }

  getData() {
    const param = 'example';
    this.myService.getData(param).subscribe(data => {
      console.log(data);
    });
  }
}