Validation in Angular TextBox component

import { Component } from '@angular/core';

@Component({
    selector: 'app-root',
    template: `<div class="wrap">
                <input class="e-input e-warning" type="text" placeholder="Input with warning"/>
                <div class="e-input-group e-error">
                    <input class="e-input" type="text" (focus)="focusIn($event.target)"
                    placeholder = "Input with error" (blur)="focusOut($event.target)"/>
                </div>
                <div class="e-input-group e-success">
                    <input class="e-input" type="text" (focus)="focusIn($event.target)"
                    placeholder = "Input with success" (blur)="focusOut($event.target)"/>
                </div>
               </div>`
})

export class AppComponent {
    public focusIn(target: HTMLElement): void {
        target.parentElement.classList.add('e-input-focus');
    }

    public focusOut(target: HTMLElement): void {
        target.parentElement.classList.remove('e-input-focus');
    }
}

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { AppComponent } from './app.component';
import { FormsModule } from '@angular/forms';
/**
 * Module
 */
@NgModule({
    imports: [
        BrowserModule,
        FormsModule
    ],
    declarations: [AppComponent],
    bootstrap: [AppComponent]
})
export class AppModule { }

import { platformBrowserDynamic } from '@angular/platform-browser-dynamic';
import { enableProdMode } from '@angular/core';
import { AppModule } from './app.module';

enableProdMode();
platformBrowserDynamic().bootstrapModule(AppModule);