What Is the Difference Between ES6 and Normal JS?

When building JavaScript applications today, there’s often confusion between what’s considered “normal JavaScript” and the version known as ES6. For developers stepping into the ecosystem or returning after a break, this difference can feel subtle yet deeply impactful. The challenge lies in recognizing how much modern JavaScript (often seen in frameworks like React, Vue, or even in vanilla code snippets online) relies on ES6 enhancements and how these affect everyday syntax, structure, and problem-solving approaches.

Syntax Improvements

One of the clearest differentiators between ES6 and older JavaScript is the syntax. ES5 required verbose patterns for simple operations, while ES6 introduces cleaner, more declarative forms.

For example, defining functions or managing default values before ES6 required more manual handling:

// ES5
function greet(name) {
  name = name || "Guest";
  return "Hello " + name;
}

With ES6, the same logic becomes simpler:

// ES6
const greet = (name = "Guest") => `Hello ${name}`;

This syntactical shift reduces cognitive load and encourages writing shorter, more expressive code that’s easier to maintain and refactor.

Scoping Rules

Before ES6, JavaScript had only function-level scope using var, which caused numerous issues with loops and closures. ES6 introduced let and const, giving developers the ability to control scope at the block level.

for (var i = 0; i < 5; i++) {
  setTimeout(function () {
    console.log(i); // Logs 5 five times
  }, 100);
}

With ES6:

for (let i = 0; i < 5; i++) {
  setTimeout(() => console.log(i), 100); // Logs 0 to 4
}

These changes not only improve logic but prevent bugs caused by variable hoisting or accidental reassignments in nested blocks.

String Handling

ES5 string concatenation was clunky and hard to read, especially when mixing variables and multiline content. ES6’s template literals offer a much more natural syntax.

// ES5
var message = "Hi " + user + ",\nWelcome to the app!";

// ES6
const message = `Hi ${user},
Welcome to the app!`;

Template literals have transformed dynamic HTML rendering, error messages, and any task where formatted strings are key.

Object Enhancements

Working with objects has seen massive improvements with ES6. In older JavaScript, defining objects with matching keys and values required duplication:

// ES5
var name = "Decode Fix";
var obj = { name: name };

ES6 simplifies this:

const name = "Decode Fix";
const obj = { name };

Combined with destructuring, object handling becomes far more elegant. It’s a major reason ES6 feels cleaner when working with APIs, Redux state, or configuration files.

Modules and Imports

Classic JavaScript didn’t have a native module system. Developers used IIFEs, globals, or libraries like RequireJS. ES6 introduced a clean, native solution.

// ES6
import { fetchUser } from "./api.js";
export const login = () => { /*...*/ };

This encourages file separation, better tooling, and optimized builds. The shift to modular code has been especially impactful in large applications where reusability and testability are crucial.

Asynchronous Code

ES5 handled async operations with callbacks, often resulting in deeply nested code. ES6 introduced Promises, making async flows flatter and easier to manage.

// ES5
getData(function (result) {
  parseData(result, function (parsed) {
    display(parsed);
  });
});

With Promises:

getData()
  .then(parseData)
  .then(display)
  .catch(handleError);

Later additions like async/await built on Promises, but ES6 laid the groundwork. Promises have become the default pattern in modern frontend and backend codebases.

Array Utilities

JavaScript arrays became far more powerful in ES6. While methods like forEach and map existed before, ES6 added features like find, includes, from, and spread syntax that simplify common patterns.

const ids = [1, 2, 3, 4];
const found = ids.find(id => id === 3);
const extended = [...ids, 5];

These tools make array manipulation more expressive and reduce the need for custom utility functions.

Feature Summary Table

Here’s a quick breakdown comparing features in ES5 (normal JS) and ES6:

Developer Experience

From a day-to-day perspective, writing in ES6 offers not just cleaner syntax, but better tooling support. Modern editors like VS Code provide autocompletion, IntelliSense, and linting that take full advantage of ES6’s predictability. Linters like ESLint are often configured to enforce ES6 best practices.

Moreover, ES6 helps in keeping codebases consistent and modern, especially when collaborating on teams. Teams can rely on patterns like destructuring props in React components, spreading props in JSX, and using arrow functions to handle events—all of which simplify logic and improve performance.

Practical Influence

Most tutorials, libraries, and frameworks now assume ES6 or newer. Whether exploring concepts like React component tables or building a React quiz interface, understanding ES6 is essential to follow along without friction.

Many older JS patterns still work but feel verbose or outdated in contrast. ES6 isn’t about replacing JavaScript—it’s about evolving it into a more developer-friendly toolset. Even simple differences, like using const for values that never change, send strong signals about intent and reduce bugs in team environments.

Conclusion

The gap between ES6 and earlier versions of JavaScript is more than just syntax—it reflects a philosophical shift in how developers structure and write code. ES6 has become the new normal, offering modern features that align better with real-world problems, team collaboration, and large-scale app development. For anyone working in JavaScript today, fluency in ES6 isn’t optional—it’s foundational. The difference may start with a keyword, but it ripples into code clarity, performance, and confidence in long-term maintainability.