JS112 - ES6+ Essentials

Modern JavaScript (ES6 and beyond) introduced powerful new features that make code cleaner, faster, and easier to maintain.
This lesson covers the most essential ES6+ features you will use every day.

1. let and const

Modern replacements for var.

let age = 30;
const name = "Emre";

• let can be reassigned
• const cannot be reassigned

2. Template Literals

Use backticks to embed variables inside strings.

let city = "Antalya";
let msg = `Hello from ${city}`;

Supports multi-line strings:

let text = `
Line 1
Line 2
`;

3. Destructuring

Extract values from arrays or objects easily.

Object destructuring

const user = {
  name: "Emre",
  age: 30,
};
 
const { name, age } = user;

Array destructuring

const colors = ["red", "green", "blue"];
const [first, second] = colors;

4. Spread Operator

Used for copying or merging arrays and objects.

Copy an array

const arr = [1, 2, 3];
const copy = [...arr];

Merge arrays

const merged = [...arr, 4, 5];

Copy an object

const cloned = { ...user };

5. Arrow Functions

Shorter and more modern function syntax.

const greet = () => console.log("Hello");

With parameters:

const add = (a, b) => a + b;

6. Default Parameters

function welcome(name = "Guest") {
  console.log("Hello, " + name);
}

7. Classes (OOP in JS)

class Person {
  constructor(name, age) {
    this.name = name;
    this.age = age;
  }
 
  greet() {
    console.log("Hello I'm " + this.name);
  }
}
 
const p = new Person("Emre", 30);
p.greet();

8. Modules (import / export)

Used to split code into reusable files.

Export

export const PI = 3.14;

Import

import { PI } from "./math.js";

Modules help organize large codebases.

Summary

In this lesson, you learned:

• let and const
• Template literals
• Destructuring
• Spread operator
• Arrow functions
• Default parameters
• Classes
• Modules

With this final lesson, your JavaScript Beginners Course is complete. You are now ready to build interactive web applications and continue with more advanced JS topics!