The Ultimate ES6 Features Guide: Boost Your JavaScript Skills

The Ultimate ES6 Features Guide Boost Your JavaScript Skills

Last updated on September 8th, 2023


ES6, or ECMAScript 6, is the sixth edition of the ECMAScript standard, which is the specification that JavaScript is based on. ES6 introduced significant enhancements and new features to JavaScript, improving the language’s syntax and functionality. Here are some key ES6 features along with examples:

ES6 features

1. let and const:

  • The let keyword allows you to declare block-scoped variables.
  • The const keyword is used for declaring constants that cannot be reassigned.
let x = 5;
const PI = 3.14159;

2. Arrow Functions:

  • Arrow functions provide a concise syntax for writing functions.
  • They have a lexical this binding, meaning this is retained from the surrounding code.
const multiply = (a, b) => a * b;

3. Template Literals:

  • Template literals allow embedding expressions inside a string using backticks.
  • They support multi-line strings and string interpolation.
const name = "User";
const greeting = `Hello, ${name}!`;

4. Destructuring Assignment:

Destructuring allows you to extract values from arrays or objects into variables.

const numbers = [1, 2, 3];
const [a, b, c] = numbers;

5. Spread Operator:

  • The spread operator ... expands elements of an array or object.
  • It can be used for array concatenation or object merging.
const arr1 = [1, 2, 3];
const arr2 = [4, 5, 6];
const merged = [...arr1, ...arr2];

6. Classes:

  • ES6 introduced class syntax for creating objects and defining inheritance.
  • It provides a more familiar and structured way of working with objects.
class Person {
  constructor(name) { = name;

  sayHello() {
    console.log(`Hello, ${}!`);

const person = new Person("Bob");

7. Default Parameters:

  • This ES6 features allows setting default values for function parameters.
  • If no argument is provided for a parameter, the default value is used.
function greet(name = "Guest") {
  console.log(`Hello, ${name}!`);

greet(); // Output: Hello, Guest!
greet("Alice"); // Output: Hello, Alice!

8. Object Destructuring:

  • Destructuring can be used to extract values from objects into variables.
  • It provides a convenient way to access object properties.
const person = {
  firstName: "Manendra",
  lastName: "Verma",
  age: 25

const { firstName, age } = person;
console.log(firstName); // Output: Manendra
console.log(age); // Output: 25

9. Rest Parameters:

  • The rest parameter syntax allows representing an indefinite number of arguments as an array.
  • It is useful when working with functions that accept a variable number of arguments.
function sum(...numbers) {
  return numbers.reduce((acc, curr) => acc + curr, 0);

console.log(sum(1, 2, 3)); // Output: 6
console.log(sum(4, 5, 6, 7)); // Output: 22

10. Modules:

  • ES6 introduced a standardized module system for JavaScript.
  • Modules allow splitting code into separate files and importing/exporting functionality between them.
// math.js
export const add = (a, b) => a + b;
export const subtract = (a, b) => a - b;

// app.js
import { add, subtract } from "./math.js";

console.log(add(5, 3)); // Output: 8
console.log(subtract(10, 4)); // Output: 6

These ES6 features further enhance JavaScript’s capabilities and provide developers with more concise and efficient ways to write code.

Find all major ES6 features in this table

Here is a table listing some of the major ES6 features with examples:

Let and ConstBlock-scoped variableslet x = 1; const PI = 3.14;
Arrow FunctionsCompact alternative function syntaxlet func = () => console.log('Hello');
Template LiteralsInterpolate expressions in stringslet str = `Hello ${name}!`;
Default ParametersDefault value for missing parametersfunction f(x = 10) {...}
DestructuringExtract data from objects/arrays into variableslet {prop1, prop2} = object; let [var1, var2] = array;
Rest/SpreadRepresent variable number of function argumentsfunction f(...args) { } let arr2 = [...arr1];
PromisesAsync operation representationreturn new Promise((resolve, reject) => {});
ClassesES6 class syntaxclass Person { constructor(){ } }
ModulesImport/export modulesimport {func} from 'module'; export class MyClass {}
IteratorsLow-level iteration protocollet it = someObj[Symbol.iterator]();;
GeneratorsYield keywword, function* syntaxfunction* myGen(){ yield 1; yield 2; }
Map/SetBuilt-in map and set objectslet map = new Map(); let set = new Set();
ES6 features

Frequently Asked Questions

  1. What are arrow functions in ES6?

Arrow functions provide a concise syntax for writing anonymous function expressions. They make code more compact by dropping the function and return keywords.

  1. How do template literals work in ES6?

Template literals use backticks “ and allow embedding expressions ${expression} for string interpolation. They provide an easier way to build strings spanning multiple lines.

  1. What is destructuring assignment in ES6?

Destructuring allows unpacking arrays or objects into distinct variables in a succinct way. For example: const {name, age} = person;

  1. What are default parameters in ES6 functions?

Default parameters allow defining a default value for a parameter if no argument is passed for it. For example: function f(x = 10) {}

  1. How can we write asynchronous code using promises in ES6?

Promises provide a standard way of writing async code that executes after a task completes. They can be chained with .then() and .catch() rather than nesting callbacks.


ES6 (ECMAScript 2015) was a major update to JavaScript that added many new capabilities to the language. Some of the most notable ES6 features include arrow functions, classes, template literals, destructuring assignments, default parameters, promises, and generators. Together these new syntax improvements and constructs have made JavaScript development more productive, concise, and expressive. Developers today can write more readable and maintainable code using these modern ES6 idioms and patterns. Concepts like promises have enabled entirely new asynchronous programming techniques. The extensive additions in ES6 features have helped position JavaScript as a versatile modern language capable of building robust large-scale applications.

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