JavaScript, often abbreviated as JS, is one of the most popular and versatile programming languages used primarily for creating interactive web pages and dynamic web applications. Over the years, JavaScript has undergone several revisions and improvements. One of the most significant updates was the release of ES6, also known as ECMAScript 2015.

In this article, we will explore the difference between JavaScript (JS) and ES6, explaining their definitions, features, and how ES6 improves upon traditional JavaScript.

What is JavaScript (JS)?

JavaScript is a high-level, interpreted scripting language that was first introduced in 1995 by Brendan Eich while working at Netscape Communications. It is primarily used for client-side web development, meaning it allows developers to create interactive web pages that respond to user actions like clicks, form submissions, mouse movements, etc. JavaScript is often used in combination with HTML and CSS to build modern web applications.

JavaScript is a versatile language that supports multiple programming paradigms, including:

• Procedural programming
• Object-oriented programming (OOP)
• Functional programming

Since JavaScript is interpreted, it runs directly in the browser without requiring compilation. This makes it one of the core technologies of the web alongside HTML and CSS.

What is ECMAScript (ES)?

Before we dive into ES6, it is important to understand what ECMAScript (ES) is. ECMAScript is the official specification or standard for scripting languages, on which JavaScript is based. It is maintained by ECMA International, specifically by a group called Technical Committee 39 (TC39).

The ECMAScript standard defines the syntax, types, operators, and other features that JavaScript implements. JavaScript is essentially an implementation of ECMAScript.

Every year, the TC39 group releases new versions of ECMAScript to standardize features that will be added to JavaScript. These versions include major updates and changes to the language, introducing new syntax and capabilities.

What is ES6?

ES6, officially known as ECMAScript 2015, is the sixth major version of the ECMAScript specification. It was released in June 2015, and it brought significant changes and new features to JavaScript. Before ES6, the most recent major update was ES5 (released in 2009), which improved JavaScript with methods like JSON.parse() and Object.create(), among others.

ES6 represents a major step forward in JavaScript’s evolution, and it laid the foundation for modern JavaScript development. With ES6, many of the features and syntax we now consider “standard” in JavaScript were introduced.

Key Differences Between ES6 and JavaScript

While JavaScript refers to the programming language as a whole, ES6 refers to a specific version or update to JavaScript. Essentially, ES6 is a version of JavaScript that introduced new features and improvements to the language.

Here are some key ES6 features that distinguish it from older versions of JavaScript:

1. Let and Const (Variable Declaration)

Before ES6, JavaScript only had var for variable declarations. This could lead to issues with variable scope, especially in loops or conditionals.

ES6 introduced two new ways to declare variables: let and const.

• let provides block-scoping, meaning it is limited to the block or statement where it is defined (like inside a loop or a function). This solves many issues with the function-scoping behavior of var.
  let x = 10;
if (true) {
let x = 20; // This x is different from the outer x
console.log(x); // Output: 20
}
console.log(x); // Output: 10

• const also provides block-scoping but is used to declare constants. Once a variable is assigned with const, its value cannot be reassigned.
  const pi = 3.14;
pi = 3.14159; // Error: Assignment to constant variable.


2. Arrow Functions (Fat Arrow Syntax)

ES6 introduced arrow functions, a shorter and more concise way of writing functions. Arrow functions also have the benefit of lexical scoping for the this keyword, which can make them easier to work with in certain scenarios (such as callbacks).

• Traditional function:
  function add(a, b) {
return a + b;
}

• Arrow function:
  const add = (a, b) => a + b;


3. Template Literals

Template literals allow for string interpolation, meaning you can embed expressions inside a string without having to concatenate them manually.

• Traditional string concatenation:
  var name = "Alice";
var greeting = "Hello " + name + "!";

• Using template literals:
  let name = "Alice";
let greeting = `Hello ${name}!`;


Template literals also support multi-line strings without the need for escape characters.

4. Destructuring Assignment

ES6 introduced destructuring, which allows you to unpack values from arrays or properties from objects into distinct variables.

• Array destructuring:
  let arr = [1, 2, 3];
let [a, b] = arr;
console.log(a); // Output: 1
console.log(b); // Output: 2

• Object destructuring:
  let person = { name: 'John', age: 30 };
let { name, age } = person;
console.log(name); // Output: John
console.log(age); // Output: 30


5. Classes (Object-Oriented Programming)

ES6 introduced a cleaner syntax for creating and working with classes, a key feature for object-oriented programming. Before ES6, JavaScript used function constructors and prototypes to simulate classes.

• ES6 class syntax:
  class Person {
constructor(name, age) {
this.name = name;
this.age = age;
}greet() {
  console.log(`Hello, my name is ${this.name}`);
  }
  }

  const john = new Person(‘John’, 30);
  john.greet(); // Output: Hello, my name is John

6. Promises

ES6 introduced Promises to handle asynchronous operations more effectively. Promises represent the eventual completion (or failure) of an asynchronous operation, providing a cleaner alternative to callback functions.

• Example of a promise:
  let promise = new Promise((resolve, reject) => {
let success = true;
if (success) {
resolve("Operation succeeded");
} else {
reject("Operation failed");
}
});promise
  .then(result => console.log(result))
  .catch(error => console.log(error));

7. Modules

ES6 introduced native modules for structuring JavaScript code into reusable pieces. Before ES6, developers had to rely on libraries like CommonJS or RequireJS to achieve modularization.

• Exporting a module:
  // math.js
export function add(a, b) {
return a + b;
}

• Importing a module:
  // main.js
import { add } from './math';
console.log(add(2, 3)); // Output: 5


8. Default Parameters

ES6 allows you to define default values for function parameters, so if no argument is provided, the default value is used.

Conclusion

In summary, JavaScript is the programming language used for building interactive web applications, while ES6 (ECMAScript 2015) is a specific version of the JavaScript language that introduced many modern features like let/const, arrow functions, template literals, destructuring, classes, promises, modules, and more. These features have made JavaScript more powerful, concise, and easier to work with, improving both development speed and maintainability.

If you’re working with modern JavaScript, you’re likely using ES6 or newer versions (like ES7, ES8, etc.), as these improvements have become essential in writing cleaner, more efficient code.