JavaScript is a scripting language that allows you to create dynamic and interactive web pages. While HTML structures the content, JavaScript makes it functional—like toggling buttons, opening forms, or handling user input.

JavaScript in LWC: The Basics

Every LWC component has a JavaScript file (.js) that defines its logic. It connects with the HTML file to modify content, handle events, and perform calculations.

The following is a simple login page that uses HTML and Javascript to validate user credentials.

function validateLogin() {
  let username = this.template.querySelector('username').value;
  let password = this.template.querySelector('password').value;

  if (!username || !password) {
    console.log('Please enter a username and password');
    return true;
  }
}