Javascript ES5 and ES6 Overview

Intro

One of the most popular programming languages used in web development is JavaScript. It is a powerful and flexible language that can be used to make dynamic and interactive web applications. JavaScript has changed over the years, and new features and improvements have been added to make it even more powerful and useful.

The release of ECMAScript 6 (ES6), which added many new features and improvements to the language, was one of the most important changes to JavaScript. ES6 added many new features, but it also made some changes that can change how you write JavaScript code.

In this article, we'll look at the differences between ES5 and ES6 in JavaScript, including the new features that ES6 adds and the changes you may need to make to your code to use these features. We'll also talk about how to make sure your code works on different browsers. By the end of this article, you should have a good idea of how ES5 and ES6 are different and how to use the newest and best JavaScript features to make better web applications.

Examples of the differences between ES5 and ES6 syntax:

Declaring variables:

The var keyword in ES5 is used to declare global variables that can be reused in different contexts. To declare a variable in ES6 that can be reassigned but not redeclared, use the let keyword; to declare a variable that cannot be reassigned or redeclared, use the const keyword.

ES5:

var x = 4;
var y = 83;

ES6:

let x = 4;
const y = 83;

Defining functions:

The function keyword is used to define a function in ES5. With ES6, you can define a function with minimal overhead by using the => syntax, which is what's known as an arrow function.

ES5:

function add(x, y) {
  return x + y;
}

ES6:

const add = (x, y) => {
  return x + y;
}

Creating classes:

A class is defined in ES5 by a constructor function and a prototype. The class syntax in ES6 is used to define classes and their associated methods.

ES5:

function Person(name) {
  this.name = name;
}
Person.prototype.sayHello = function() {
  console.log('Hello, my name is ' + this.name);
}

var person = new Person('John');
person.sayHello();

ES6:

class Person {
  constructor(name) {
    this.name = name;
  }
  sayHello() {
    console.log(`Hello, my name is ${this.name}`);
  }
}

const person = new Person('John');
person.sayHello();

Browser Compatibility:

It is important to remember that not all browsers can use all of ECMAScript 6's features (ES6). Older browsers may not support ES6 features at all or may need a transpiler to turn the code into a form they can understand.

A transpiler is software that changes code written in one programming language, like ES6, into another (ES5). This lets you use newer parts of a language, even if not all browsers can handle them.

You can use a site like caniuse.com to determine if ES6 features work in different browsers. This website has information about how different browsers support other web technologies, such as ECMAScript 6.

If you want your code to work in older browsers that don't support all of ES6's features, you can use a transpiler like Babel to turn your code into a form that those browsers can understand. So, you can use the newest and best JavaScript features without worrying about problems with compatibility.

It's important to note that as browser support for ES6 improves, you'll need to use a transpiler to worry less about compatibility issues less and less. But it's always a good idea to make sure your code works in the browsers you want it to to ensure it does what you want.

Which compilers are available to me?

You can use a compiler to convert your ECMAScript 6 (ES6) code into a version that is compatible with older browsers. Some popular choices are:

• Babel: Babel is a popular transpiler that can convert your ES6 code into a version that works with a variety of browsers. It has a large user base and is actively maintained.
• TypeScript: A superset of JavaScript, TypeScript is a programming language. It incorporates ES6 features as well as additional type checking and other features. TypeScript can be used to transpile your code into an older browser-compatible version.
• Traceur: Traceur is another transpiler that can convert your ES6 code into an older browser-compatible version. It was created by Google and supports a wide range of ES6 features.
• Closure Compiler: The Closure Compiler is a Google tool that can minify and optimize your code, including converting ES6 code into an older browser-compatible version.

These are just a few of the compilers available for transpiling ES6 code. There are numerous other choices available, and the best one for you will be determined by your specific needs and requirements.

It's worth noting that as browser support for ES6 improves, using a transpiler or worrying about compatibility issues becomes less necessary. However, if you need to support older browsers or use the most recent JavaScript features, a transpiler can be a useful tool to have in your toolbox.

Conclusion:

So, ES6 is a newer version of JavaScript that brought many new features and improvements to the language. Some cool new things you can do with ES6 include using let and const to declare variables with block scope, using arrow functions to write more concise and readable code, and defining classes with more object-oriented syntax.

But here's the catch: not all web browsers support these new features. If you want your web application to work on all browsers, you might need to use a transpiler tool to convert your ES6 code into an older version of JavaScript that is more widely supported.

You can use a few different transpilers, like Babel or TypeScript, that will do the conversion for you. The good news is that as time goes on, more and more browsers are adding support for ES6 features, which means that you may be fine with using a transpiler forever.

In the end, understanding ES6 is an important part of staying up-to-date with the latest developments in web development. By keeping up with the latest features and improvements, you can build more powerful, efficient, and maintainable web applications that work well on various browsers.