ES6/ES2015: JavaScript has finally grown up

ECMAScript 2015 introduces classes, arrow functions, modules, Promises, and destructuring. A guide to the most important changes and how to start using them today.

The biggest JavaScript update in 6 years¶

ES6 (officially ECMAScript 2015) is the most significant update to the language since ES5 in 2009. It introduces dozens of new features that address pain points developers have been dealing with for years.

Key additions include let and const for block scoping, arrow functions, template literals, destructuring, default parameters, rest/spread operators, and a native module system.

Arrow functions and lexical this¶

Arrow functions are not just shorter syntax — they solve the notorious this context problem:

// ES5 — "that = this" hack
var self = this;
button.addEventListener('click', function() {
  self.handleClick();
});

// ES6 — lexical this
button.addEventListener('click', () => {
  this.handleClick();
});

Destructuring and template literals dramatically improve code readability:

const { name, age, ...rest } = user;
const greeting = `Hello ${name}, you are ${age} years old.`;

Promises and modules¶

Native Promises finally standardise asynchronous operations without callback hell:

fetch('/api/users')
  .then(res => res.json())
  .then(users => console.log(users))
  .catch(err => console.error(err));

The module system with import/export replaces CommonJS and AMD in browser code. Static analysis enables tree shaking — eliminating unused code during bundling.

How to start with ES6 today¶

Browser support is still incomplete, but the Babel transpiler lets you write ES6 code and compile it to ES5. Recommended setup:

• Babel for transpilation
• Webpack or Browserify for bundling
• ESLint with ES6 rules for consistency
• Gradual adoption — start with let/const, arrow functions, and template literals

Conclusion: an investment in the future¶

ES6 transforms JavaScript from a quirky scripting language into a modern, expressive platform. The investment in switching to ES6 pays off in team productivity, code readability, and easier maintenance. Do not start a new project without ES6.