I am learning flutter from JustAcademy, They provide very much great environment where people gather and work simultaneously. totally project based training institute.
Awesome Experience. I am a Front-end Web Designer working at Star India for 3 years now. I applied for Full-stack development and my experience has been phenomenal & they really do help with placements exceptionally. Thank you Roshan sir so much.
If you have ever opened an old JavaScript file and felt like you were reading a different language, you have already met the gap that the most important javascript es6 features closed. Before 2015, writing JavaScript meant juggling var, wrestling with the keyword this, gluing strings together with plus signs and inventing your own patterns just to organise code. ES6 arrived and quietly rearranged the furniture. Developers who learn es6 javascript properly find that code gets shorter, clearer and far easier to hand over to a teammate.
This guide is written for people in Delhi, Noida, Gurugram and across the NCR who want to learn es6 the right way, with real examples and honest explanations instead of memorised syntax. If you would rather learn with a trainer who answers your doubts in the moment, you can explore the JavaScript course or book a free demo session and see how a live interactive, instructor led class actually feels before you commit to anything.
Let us start with the story behind the name, because it helps everything else make sense.
ES6 is short for ECMAScript 6, the sixth edition of the standard that JavaScript follows. You will also see it called ES2015, because the standards body moved to naming editions by year. So when someone says es6 2015 or es6 es2015, they mean exactly the same release. The version before it, ES5, dates back to 2009 and was the backbone of the web for years.
The move from es5 to es6 was the largest single update JavaScript has ever received. It added new ways to declare variables, a shorter function syntax, classes, modules, promises, template strings and more. Nothing from ES5 was removed, which is why old code still runs. The new ecmascript 6 syntax simply sits beside the old one, and over time it became the default.
The honest way to understand the es6 standard is to think about the daily annoyances it removed. Scope bugs caused by var leaking out of loops. Callback pyramids that made asynchronous code unreadable. Constructor functions and prototype chains that confused every beginner. Long string concatenations that broke the moment someone forgot a space.
Each major feature in this release answers one of those pain points. That is a useful lens as you read on. Do not try to memorise a list of es6 new features. Ask yourself what problem each one solves, and you will remember it without effort.
Many learners search for es5 es6 es7 as if they were three separate languages. They are not. ES7, released in 2016, was a small update that added the exponent operator and Array.prototype.includes. After that, JavaScript moved to a yearly release rhythm, and each edition added a handful of focused features.
The takeaway is simple. ES6 was the big leap, and everything after it has been a gentle climb on top of that foundation. If you understand javascript es6 concepts well, picking up what came later feels natural.
Variables are the first thing every beginner touches, and this is where the difference between old and new JavaScript shows up immediately. In es6 in javascript, let and const replaced var for almost every situation, and understanding why will save you from a whole category of bugs.
A variable declared with var belongs to the entire function, no matter which braces you wrote it inside. That sounds harmless until a loop counter leaks out and changes something you did not expect. A variable declared with let stays inside the block where you created it.
javascript
for (let i = 0; i < 3; i++) { setTimeout(() => console.log(i), 100); } // prints 0, 1, 2
With var in the same loop, you would see 3 printed three times, because every callback shares one variable. With let, each pass through the loop gets its own copy. This single difference explains a large share of interview questions about scope, and it is a perfect example of es5 to es6 improvement.
Beginners often assume const makes a value frozen. It does not. It only means the variable name cannot be pointed at something else.
javascript
const student = { name: "Aarav", city: "Delhi" }; student.city = "Noida"; // allowed // student = {}; // not allowed, throws an error
The object itself can still change. If you truly want an object locked, you reach for Object.freeze. Knowing this distinction makes you sound like someone who has written real code rather than copied a tutorial.
Here is a rule that works in almost every project. Start with const for everything. If you later discover the value needs to be reassigned, change it to let. Avoid var completely in new code. This habit keeps your intent obvious, because anyone reading a const knows that name will never be reassigned, which reduces what they need to hold in their head.
If you are following this javascript es6 tutorial for beginners and want to reinforce these basics by building something, the project ideas in this guide to JavaScript projects every beginner should build for a portfolio are a great place to practise variables, scope and functions together.
If you ask a room of developers to name their favourite es6 feature, a large number will say the arrow function. The es6 arrow function gives you a shorter way to write functions, and it also changes how this behaves, which matters far more than the saved keystrokes.
A traditional function expression needs the function keyword, parentheses, braces and an explicit return. An arrow function lets you drop most of that.
javascript
// ES5 style var double = function (n) { return n * 2; }; // ES6 style const double = (n) => n * 2;
When there is one expression, the value is returned automatically. When you need several statements, you use braces and write return yourself. For a single parameter you may even drop the parentheses, though many teams keep them for consistency. This is the syntax you will see in almost every modern codebase, from small scripts to large React applications.
Here is the part that trips people up. A regular function decides what this means based on how it is called. An arrow function does not create its own this. It borrows it from the surrounding code.
javascript
const timer = { seconds: 0, start() { setInterval(() => { this.seconds++; console.log(this.seconds); }, 1000); } };
In the old days you had to write var self = this or use .bind(this) to make a callback behave. The arrow function removes that ritual. This is why es6 functions in javascript feel so much calmer inside classes and event handlers.
One warning worth remembering: do not use an arrow function as an object method when you need this to refer to the object itself, and do not use it as a constructor. Arrow functions are a tool, not a replacement for every function you write.
The function es6 improvements go beyond arrows. Default parameters let you define a fallback value right in the signature.
javascript
function greet(name = "friend", city = "Delhi") { return `Hello ${name} from ${city}`; }
Rest parameters collect the leftover arguments into a real array, which replaces the awkward arguments object from earlier JavaScript.
javascript
const total = (...numbers) => numbers.reduce((sum, n) => sum + n, 0); total(10, 20, 30); // 60
Together, arrows, defaults and rest parameters make the way you write a function es6 style feel closer to how you would explain the idea out loud.
Strings are everywhere in real applications. Error messages, user greetings, API URLs, HTML snippets. Before ES6, building them was tedious and error prone. Template literals fixed that so thoroughly that few developers ever go back.
A template literal uses backticks instead of quotes, and anything inside ${} is evaluated as JavaScript.
javascript
const learner = "Meera"; const course = "JavaScript"; const message = `Welcome ${learner}, your ${course} class starts at ${9 + 1} AM.`;
Compare that with the old version, where you had to close the string, add a plus sign, open it again and hope you did not miss a space. When people search for template strings in javascript or template strings js, this is exactly the feature they are looking for, and it is one of the easiest wins for any beginner.
Before backticks, writing a multiline string meant using \n or joining an array. Now you simply press enter.
javascript
const card = ` Name: ${learner} Course: ${course} City: Delhi `;
This makes es6 template literal syntax especially pleasant when you are generating HTML, email bodies or log messages. Just be aware that the indentation inside the backticks becomes part of the string, so format it with that in mind.
Tagged templates are a more advanced use of template literals in es6. You put a function name in front of the backticks, and that function receives the string pieces and the values separately.
javascript
function highlight(strings, ...values) { return strings.reduce((out, str, i) => { return out + str + (values[i] ? `[${values[i]}]` : ""); }, ""); } highlight`Hello ${learner}, welcome to ${course}`;
Libraries use this idea for styled components and safe query building. You will not need it on day one, but knowing it exists puts you ahead of many people who only skimmed a js template literals article.
If arrow functions are the most loved feature, destructuring and spread are the ones that quietly transform how you handle data. Almost every API response you ever touch is an object or an array, and these tools let you work with them without repetitive code.
Es6 object destructuring lets you pull values out of an object and into variables in a single line.
javascript
const user = { name: "Kabir", role: "developer", city: "Gurugram" }; // ES5 style var name = user.name; var role = user.role; // ES6 style const { name, role, city } = user;
You can rename variables, set defaults and dig into nested objects as well.
javascript
const { name: fullName, country = "India" } = user;
Destructuring also works beautifully in function parameters, which is why you see it all over React components. Passing an object and unpacking it right in the parentheses makes a function’s expectations visible at a glance.
Arrays can be unpacked by position.
javascript
const [first, second, ...others] = ["HTML", "CSS", "JavaScript", "React"];
A neat trick that shows how readable this has become is swapping two values without a temporary variable.
javascript
let a = 1; let b = 2; [a, b] = [b, a];
The three dots can mean two opposite things depending on where you use them. When they expand something, that is spread. When they collect something, that is rest. The es6 spread operator expands an array into individual elements.
javascript
const frontend = ["HTML", "CSS"]; const stack = [...frontend, "JavaScript", "React"];
It is also the cleanest way to copy or merge arrays without touching the original. The same idea extends to objects, which is why searches for spread operator in javascript object are so common.
javascript
const basic = { name: "Riya", city: "Delhi" }; const updated = { ...basic, city: "Noida", active: true };
The later keys win, so city becomes Noida. This pattern is the foundation of state updates in React, where you never mutate state directly but create a new copy with the change applied. It is one of the most practical javascript es6 examples you can learn.
The rest syntax works inside destructuring too. When you write const { name, ...remaining } = user, everything except name lands in a new object. This is handy when you want to strip out a field before sending data somewhere else.
JavaScript always had objects and prototypes, but the way to organise bigger programs was awkward. ES6 gave the language two tools that make large projects manageable: classes and modules.
An es6 class is syntax built on top of the prototype system that already existed. It does not turn JavaScript into Java, but it makes the common patterns readable.
javascript
class Course { constructor(title, mode) { this.title = title; this.mode = mode; } describe() { return `${this.title} is taught in ${this.mode} mode`; } } class MentorLedCourse extends Course { describe() { return `${super.describe()} with a mentor guiding every step`; } }
The constructor, extends and super keywords give you inheritance without manually wiring prototypes. If you want to go deeper into how this works, including getters, static methods and private fields, this walkthrough on JavaScript classes takes the topic apart with patience.
Before ES6, sharing code between files meant global variables or third party tools. Native modules changed that.
javascript
// math.js export const square = (n) => n * n; export default function add(a, b) { return a + b; } // app.js import add, { square } from "./math.js";
Every file gets its own scope, dependencies are explicit and bundlers can remove code you never use. When you move on to frameworks, you will write import statements in every single file, so it pays to understand them now.
This is where the idea of es6 to es5 conversion comes in. Tools like Babel read modern syntax and output older equivalents, so your es6 code can run in browsers that do not support it. These days almost every browser supports the main features natively, but build tools still handle compatibility behind the scenes, so it is useful to know what is happening in your pipeline.
Arrays and objects handled everything in ES5, sometimes awkwardly. ES6 added purpose built collections and a cleaner way to loop over them.
A Set stores unique values, which makes removing duplicates a one line job.
javascript
const cities = ["Delhi", "Noida", "Delhi", "Gurugram", "Noida"]; const unique = [...new Set(cities)];
A Map stores key value pairs like an object, but keys can be any type, order is preserved and size is easy to read.
javascript
const scores = new Map(); scores.set("Aarav", 92); scores.set("Meera", 88); console.log(scores.size); // 2
Reach for a Map when keys are dynamic or not strings. Keep plain objects for fixed, structured records.
The for of loop walks through the values of anything iterable, including arrays, strings, Maps and Sets.
javascript
for (const city of unique) { console.log(city); }
It avoids the index bookkeeping of a classic loop and the key confusion of for in. Once you see how often you loop over data, you realise how much cleaner your es6 code becomes.
Generators are functions that can pause and resume, producing values one at a time.
javascript
function* counter() { let n = 1; while (true) { yield n++; } }
You will not write generators daily, but they sit underneath several advanced patterns and help you appreciate how async code works internally. Treat them as a concept to revisit after the core features feel comfortable.
Most real programs wait for something: a server, a file, a database, a timer. Before ES6, the standard answer was nested callbacks, and anyone who has seen the callback pyramid knows how unreadable it gets.
A promise represents a value that will arrive later. It is either pending, fulfilled or rejected, and you attach handlers to deal with each outcome.
javascript
fetch("https://api.example.com/courses") .then((response) => response.json()) .then((data) => console.log(data)) .catch((error) => console.error(error));
Chaining flattens the pyramid into a straight line, and one catch can handle failures from any step. Promises are the backbone of modern web development, and the es6 feature set made them native to the language.
Async and await arrived in the ES2017 edition, and they build directly on promises. They let asynchronous code read like ordinary top to bottom logic.
javascript
async function loadCourses() { try { const response = await fetch("https://api.example.com/courses"); const data = await response.json(); return data; } catch (error) { console.error(error); } }
If you understand promises from ES6, async and await take about an afternoon to feel natural.
Do not rush past this section. Asynchronous thinking is the point where many beginners stall, because it asks you to imagine code that does not run in the order it is written. A mentor led session helps enormously here, since a trainer can draw the event loop on a whiteboard and walk through exactly what happens, which is far harder to absorb from a video alone. If you want to feel that difference, you can register for a free demo class and ask your doubts live.
Sometimes the quickest way to see progress is to put the old and the new next to each other. This is also the part of a javascript es6 tutorial that people bookmark for revision.
| Task | ES5 approach | ES6 approach |
|---|---|---|
| Declare a variable | var with function scope | let and const with block scope |
| Write a short function | function keyword with return | Arrow function with implicit return |
| Build a string | Plus signs and quotes | Template literals with ${} |
| Pull values from an object | One assignment per property | Object destructuring |
| Copy or merge arrays | concat or slice | Spread operator |
| Default argument | Check undefined inside the body | Default parameters |
| Create a reusable blueprint | Constructor function and prototype | class with extends |
| Share code between files | Global scripts or external tools | import and export modules |
| Handle async results | Nested callbacks | Promises, then async and await |
| Store unique values | Array with manual checks | Set |
If you are preparing for interviews, a few lines are worth memorising. let and const are block scoped, const prevents reassignment but not mutation, arrow functions inherit this, spread expands and rest collects, template literals use backticks, and modules give each file its own scope. These are the javascript es6 concepts interviewers return to again and again.
One more reason ES6 matters is that it opened the door to a functional style. Arrow functions, destructuring and spread pair beautifully with map, filter and reduce.
javascript
const prices = [120, 450, 80, 300]; const discounted = prices .filter((p) => p > 100) .map((p) => p * 0.9);
This is es6 functional programming in its simplest form: small functions, no mutation, data flowing from one step to the next. You will see this style in React, Redux and almost every modern JavaScript library.
Reading about features is the easy half. The harder and more rewarding half is using them until they become instinct. Many learners in Delhi tell the same story: they watch tutorials for weeks, feel confident, and then freeze in front of a blank editor. The cure is deliberate building.
Start with a to do list, a quiz app, a weather widget or an expense tracker. Force yourself to use const, arrow functions, destructuring and template literals in every file. Then refactor an old ES5 snippet into modern syntax and compare the two. If you need ideas, revisit the portfolio project suggestions for beginners and pick two that look interesting.
Modern frameworks assume you already know these features. React components use arrow functions, destructuring and spread constantly. Node.js servers use modules and promises. If you aim to build complete products, a structured path such as the MERN stack developer bootcamp takes your es6 javascript foundation and extends it into React, Node, Express and MongoDB with live online delivery for learners in Delhi.
Some learners come from a Java background and wonder how JavaScript fits into a longer career plan. If that sounds like you, this full stack Java developer roadmap is worth reading alongside this guide, because it shows how front end skills and back end skills combine.
JavaScript fluency also carries into mobile work. Cross platform thinking, component based design and clean asynchronous code all transfer smoothly. When you are ready to explore apps, you can look at Flutter training for a single codebase approach, or choose a native route through Android app development or iOS training. You do not need to decide today. Strong fundamentals simply keep every one of those doors open.
Free videos and documentation are wonderful, and no honest trainer would tell you otherwise. The trouble is not the quality of the material. It is the missing structure, feedback and accountability. Learners who study alone often skip the uncomfortable topics, copy code they do not understand and never find out which habits are quietly wrong.
In live interactive sessions, you type code while the trainer watches, you ask a question the moment it appears and you get corrected before a bad habit settles in. An instructor led session gives your learning a spine, with each concept building on the last, from variables to functions to asynchronous code to frameworks. A mentor led session goes one step further, because someone reviews your projects, points out what an interviewer would notice and helps you decide what to learn next.
JustAcademy is an ISO certified technology training institute with classroom training in Mumbai and Pune, and live interactive online courses available globally. For learners in Delhi and the wider NCR, the live online format brings the same instructor led and mentor led experience to your screen without the commute. Many learners search for the best course in Mumbai when they want classroom energy, and others prefer to join from home and still get the same curriculum, the same doubt clearing and the same attention.
Placement support runs alongside the training, covering resume reviews, mock interviews and guidance on how to present projects. The goal is not to hand you a certificate and wish you luck. It is to help you walk into an interview and explain, with confidence, why you chose const over let or how a closure works.
Attend a demo, watch how the trainer teaches, notice whether your questions are welcomed and see if the pace suits you. If it feels right, continue. If not, you have lost nothing. A good institute is happy for you to evaluate it before you decide.
The javascript es6 features covered here are not trivia. They are the everyday vocabulary of modern development. let and const make scope predictable, arrow functions tidy up logic, template literals make strings readable, destructuring and the spread operator make data handling light, classes and modules bring order to bigger projects, and promises make asynchronous work manageable. Moving from es5 to es6 is less about learning a new language and more about learning to say the same things more clearly.
If you are just starting, take this javascript es6 tutorial for beginners slowly. Type every example yourself, break it on purpose and fix it. Then build something small and keep improving it. When you want a guide who can speed up that journey with live interactive, instructor led and mentor led sessions, JustAcademy is ready to help, whether you join our classrooms in Mumbai and Pune or learn online from Delhi with placement support behind you.
Ready to take the next step?
Join a free demo class and experience live interactive training for yourself: Register for the Free Demo
Want the full details on courses, duration and outcomes: Download the Brochure
A practical, example driven guide to ES6 JavaScript for learners in Delhi who want to write modern code, think like a developer and get job ready with live instructor led and mentor led training
From your first Angular app to real time dashboards, here is a practical, mentor backed list of angular projects for practice, with source code thinking, live interactive sessions and placement support.
A mentor led guide for Delhi developers, covering the React questions interviewers actually ask and answers you can say out loud with confidence
From a humble to do list to a Node JS backend, here are the javascript project ideas that actually teach you something and give recruiters a reason to click your GitHub link.
A straight talking guide for Delhi freshers, career switchers and non tech graduates on choosing the right IT certification, and why live interactive, instructor led and mentor led training makes the difference
A grounded, honest guide for Delhi learners on skills, salaries, jobs and the learning path behind each IT career, backed by live, instructor led and mentor led training
A straight talking guide for Delhi learners on what mobile app developers really earn, which skills raise the number, and how live, mentor led training can shorten the road from beginner to hired.
A practical guide for Delhi learners covering react native app ideas for beginners, live mentor led practice, and a portfolio that actually gets interviews
A plain spoken guide to budgets, build times, team choices and the learning path behind every dependable Flutter project
A practical, honest walkthrough of Swift, Xcode, Windows workarounds, Flutter, React Native and the career paths that open up once you can build for Apple devices
