import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { ThermalPrintModule } from 'ng-thermal-print'; //add this line
import { AppComponent } from './app.component';

@NgModule({
   declarations: [
        AppComponent
    ],
    imports: [
        BrowserModule,
        ThermalPrintModule //add this line
    ],
    providers: [],
    bootstrap: [AppComponent]
})
export class AppModule { }

import { PrintService, UsbDriver, WebPrintDriver } from 'ng-thermal-print';
import { Component } from '@angular/core';
import { PrintDriver } from 'ng-thermal-print/lib/drivers/PrintDriver';

@Component({
    selector: 'app-root',
    templateUrl: './app.component.html',
    styleUrls: ['./app.component.css']
})
export class AppComponent {
    status: boolean = false;
    usbPrintDriver: UsbDriver;
    webPrintDriver: WebPrintDriver;
    ip: string = '';

    constructor(private printService: PrintService) {
        this.usbPrintDriver = new UsbDriver();
        this.printService.isConnected.subscribe(result => {
            this.status = result;
            if (result) {
                console.log('Connected to printer!!!');
            } else {
            console.log('Not connected to printer.');
            }
        });
    }

    requestUsb() {
        this.usbPrintDriver.requestUsb().subscribe(result => {
            this.printService.setDriver(this.usbPrintDriver, 'ESC/POS');
        });
    }

    connectToWebPrint() {
        this.webPrintDriver = new WebPrintDriver(this.ip);
        this.printService.setDriver(this.webPrintDriver, 'WebPRNT');
    }

    print(driver: PrintDriver) {
        this.printService.init()
            .setBold(true)
            .writeLine('Hello World!')
            .setBold(false)
            .feed(4)
            .cut('full')
            .flush();
    }
}

<strong>Status: {{status}}</strong>
<div>
    <input [(ngModel)]="ip" type="text" name="ip" placeholder="IP of printer with WebPRNT">
    <button (click)="connectToWebPrint()">Connect to WebPRNT</button>
</div>

<div>
    <button (click)="requestUsb()">Connect to USB</button>
</div>

<div>
    <button (click)="print()" [disabled]="status === false"> Print!</button>
</div>