Sending get request in ionic 4

Ionic Framework
1

I want to send get request in ionic onClick but when i run app the screen is blank before onClick

Here is the code of ----------------------------------------------------------------------------------- app.module.ts

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { RouteReuseStrategy } from '@angular/router';

import { IonicModule, IonicRouteStrategy } from '@ionic/angular';
import { SplashScreen } from '@ionic-native/splash-screen/ngx';
import { StatusBar } from '@ionic-native/status-bar/ngx';

import { AppComponent } from './app.component';
import { AppRoutingModule } from './app-routing.module';

import { HTTP } from '@ionic-native/http';


@NgModule({
  declarations: [AppComponent],
  entryComponents: [],
  imports: [
    BrowserModule,
    IonicModule.forRoot(),
    AppRoutingModule
  ],
  providers: [
      HTTP,
    StatusBar,
    SplashScreen,        
    { provide: RouteReuseStrategy, useClass: IonicRouteStrategy }
  ],
  bootstrap: [AppComponent]
})
export class AppModule {}

and here is the code of --------------------------------------------------------------------------- home.page.ts

import { Component } from '@angular/core';
import { HTTP } from '@ionic-native/http';

@Component({
  selector: 'app-home',
  templateUrl: 'home.page.html',
  styleUrls: ['home.page.scss'],
})
export class HomePage 
{

constructor(private http: HTTP) {}

showAlert() 
{

this.http.get(SERVER_URL, {}, {})
  .then(data => {

    console.log(data.status);
    console.log(data.data); // data received by server
    console.log(data.headers);

  })
  .catch(error => {

    console.log(error.status);
    console.log(error.error); // error message as string
    console.log(error.headers);

  });
}


}

Here is the code of home.page.html where onClick triggered.

<ion-header>
  <ion-toolbar>
    <ion-buttons slot="start">
      <ion-menu-button></ion-menu-button>
    </ion-buttons>
    <ion-title>
      Home
    </ion-title>
  </ion-toolbar>
</ion-header>

<ion-content>
    <ion-card class="welcome-card">
      <ion-img src="/assets/shapes.svg"></ion-img>
      <ion-card-header>

    <div id="container">
      <ion-list>

    <br>
      <ion-item >
        <ion-label fixed>User Name</ion-label>
        <ion-input type="text" value=""  id="rounded" [(ngModel)]="username"></ion-input>
       </ion-item>
 
    </ion-list>
  </div>

        <ion-button (click) = "showAlert()">Submit</ion-button>
        <br>
        <ion-button color="primary">light</ion-button>
      </ion-card-header>
    </ion-card>
    
</ion-content>
2

Use following :-
ionic 4 / 3
app.module.ts
import { HttpClientModule } from ‘@angular/common/http’;
import { HttpModule } from ‘@angular/http’;

@NgModule({
imports: [
HttpClientModule,
HttpModule,
]

})

home.page.ts
import { Http ,Response ,Headers, RequestOptions} from ‘@angular/http’;
import { map } from ‘rxjs/operators’;

constructor(private http: Http) { }

this.http.get(SERVER_URL,{}).pipe(map((res: Response) =>{
var data = res.json();
}));