Handle Model Change in Angular 5 Component (Two-way-binding)

you can use the (ngModelChange) directive

    <input [(ngModel)]="hello" (ngModelChange)="myFunction()"/>

code:

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

    @Component({
        selector: 'my-test',
        templateUrl: './my-test.component.html',
        styleUrls: ['./my-test.component.css']
    })
    export class MyTestComponent {
        hello: string = "bonjour";

        constructor() { }

        myFunction() {
            console.log(this.hello);
        }
    }