Code: helloWorld.js

//vh. these first 2 lines are required!
import { LightningElement } from 'lwc';
export default class HelloWorld extends LightningElement {
  //vh. 'greeting' below will be dynamic content: user can change on the fly!
  greeting = 'World';
  changeHandler(event) {
    this.greeting = event.target.value;
  }
}