Over 25 years JavaScript is active. It is a programming language that has been used by developers from all over the world. Various companies that provide web development services have used it daily for years. It has evolved significantly over that time, introducing new capabilities and grammar. It used to take years for new features to reach the language, but the current JavaScript standard is updated with new features on a yearly basis.
JavaScript ES6 included many significant modifications to the JavaScript standard. ES6 stands for ECMAScript 6; ECMAScript is another official name for JavaScript because the standard is created by the organization ECMA International.
Keep reading this blog to learn more about JavaScript ES6.
JavaScript ES6: What is it?
JavaScript ES6 is the 2015 version of JavaScript. Because of the many new capabilities given to the language by the 2015 upgrade, many developers refer to any version of JavaScript published after 2015 as “ES6” informally. Several JavaScript versions have been published since then, but ES6 still needs to acquire more traction in the development community.
JavaScript versions were named by version number until 2015. ES6 was the last JavaScript version to be titled in this manner, and it was renamed ES2015 before the end of 2015. (ECMAScript 2015).
ES6 is thus a legacy designation, and the new annual naming system is why there has been no official “ES7” or higher, despite the existence of later versions of JavaScript. The two designations are occasionally used interchangeably by developers; for example, JavaScript ES6 is frequently referred to as ES2015.
Now that you briefly know about ES6, it’s time to dig deep to learn more about it.
Reason Behind ES6 Being the Future of JavaScript
Being the first JavaScript version in a decade (after ES5), JavaScript ES6 brought modernized web capabilities in the 2010s. The new standard included a number of capabilities that developers had long desired, as well as language optimizations that made writing JavaScript programs much more accessible.
Let’s Keep reading to know more.
Improved Syntax
One of the significant improvements in ES6 is the syntax. ES6 introduces several new syntax features, such as template literals, arrow functions, and destructuring, that make the code more readable and concise. Template literals allow for multi-line strings and the interpolation of variables directly within strings.
Arrow functions offer a shorter syntax for writing functions and allow the use of the “this” keyword more intuitively. Destructuring enables you to extract values from arrays or objects and assign them to variables more elegantly.
Enhanced Object-Oriented Programming
ES6 introduces several new features that make object-oriented programming more intuitive and robust. One of the most noteworthy features is the introduction of classes, which provide a more familiar syntax for defining classes and creating objects. ES6 also includes the “super” keyword, which enables you to call the parent class’s constructor and methods from within the child class. Additionally, ES6 consists of the “extends” keyword, allowing for inheritance and subclass creation.
Improved Modules
ES6 introduces a new module system that provides a more organized way to structure and manage code. The new module system allows you to import and export modules more modularly and granularly, which helps reduce code complexity and improve maintainability. The module system also enables you to use static analysis tools to detect dependencies and optimize your code.
Enhanced Asynchronous Programming
ES6 introduces several new features that make asynchronous programming more manageable and intuitive. Introducing Promises is one of the most significant features, which provides a cleaner way to handle asynchronous operations and avoid the “callback hell” problem. Promises enable you to chain asynchronous operations and handle errors in a more organized way. ES6 also introduces the “async/await” syntax, which provides a more readable and synchronous-looking way to handle asynchronous operations.
Improved Performance
ES6 introduces several performance improvements over previous versions of JavaScript. One of the most significant improvements is the introduction of block scoping with the “let” and “const” keywords. Block scoping allows for more efficient memory management and eliminates the need for workarounds like the immediately invoked function expression (IIFE). ES6 also introduces several optimizations to built-in methods like “map“, “filter“, and “reduce” which can improve performance in many scenarios.
Better Browser Support
ES6 has been around for several years and has gained significant adoption across the web development community. Most modern browsers support ES6, and even some older browsers like Internet Explorer partially support ES6 features. Several tools and libraries have been developed to provide ES6 compatibility for older browsers, such as Babel and Polyfill.io.
Some Exclusive Features of ES6
ES6 is filled up with various features. Some of the most exclusive features are written below.
Destructuring Assignment
Destructuring assignment is a feature in ES6 that allows you to extract values from arrays or objects and assign them to variables in a more concise and convenient way. It provides a shorthand syntax to unpack values from arrays or objects into individual variables. With destructuring assignment, you can extract and assign multiple values from an array or object in a single statement.
Here’s some examples of array and object destructuring:
Array Destructuring:
Example 1:
let myArr = [1, 3, 5]
let [first, second, third] = myArr
Does the job of:
let myArr = [1, 3, 5]
let first = myArr[0]
let second = myArr[1]
let third = myArr[2]
Example 2:
const myArr = [1, 2, 3];
const [a, b, c] = myArr;
console.log(a); // Output: 1
console.log(b); // Output: 2
console.log(c); // Output: 3
Object Destructuring:
Example 1:
const myObj = { name: ‘Rajesh’, age: 25};
const { name, age } = myObj;
console.log(name); // Output: Rajesh
console.log(age); // Output: 25
Example 2:
const myObject = { one: 1, two: 2 };
const { one, two } = myObject;
console.log(one); // Output: 1
console.log(two); // Output: 2
Arrow Functions
Arrow functions are a useful feature introduced in ES6 that provide a more concise syntax for defining functions. An arrow function is a type of function that uses the `=>` syntax to define a function.
Here’s an example:
const add = (a, b) => {
return a + b;
}
In this example, the arrow function `add` takes two parameters `a` and `b`, and returns their sum. The `=>` syntax is used to define the function body, which is enclosed in curly braces. The return statement is used to `return` the result of the addition.
One of the main benefits of arrow functions is their concise syntax, which makes them easy to read and write. In addition, arrow functions have a few unique features that make them useful in certain situations:
Implicit return
If the function body consists of a single expression, you can omit the curly braces and the `return` statement, and the function will automatically return the value of the expression.
For example:
const double = (x) => x * 5;
This arrow function takes a single parameter `x` and returns `x` multiplied by 5. Since the function body consists of a single expression, the curly braces and the `return` statement can be omitted.
Lexical `this`
Arrow functions use the `this` value of the enclosing lexical scope, rather than having their own `this` value like traditional functions. This makes them useful in situations where you need to preserve the `this` value of an enclosing object, such as in event listeners or in methods that pass functions as arguments.
const myObject = {
name: ‘Esolz’,
greeting: function() {
setTimeout(() => {
console.log(`Hello, my name is ${this.name}`);
}, 1000);
}
};
myObject.greeting(); // logs “Hello, my name is Esolz” after 1 second
In this example, the `greeting` method of `myObject` uses an arrow function for the callback passed to `setTimeout`. Because the arrow function has no `this` of its own, it uses the `this` value of the enclosing `greeting` method, which is the `myObject` instance. This allows the arrow function to access the `name` property of `myObject`.
Overall, arrow functions provide a more concise and flexible way to define functions in JavaScript.
Block Scoping
Prior to ES6, there were only two types of scoping in JavaScript: global and functional. Let, and const variable declarations were introduced in ES6 and are scoped within blocks, that is, between curly brackets, including if statements switch conditions and loops.
For example:
// Global scope
var number = 5
if (number === 5) {
let a = ‘Hello’
const b = ‘Hi’
console.log(a) // Hello
console.log(b) // Hi
}
console.log(a) // ReferenceError: a is not defined
console.log(b) // ReferenceError: b is not defined
The Spread Operator
The spread operator (…) permits you to extend an iterable object where particular arguments or key-value pairs are expected. This can be used to call functions or modify object literals and strings.
For example, we can use the spread operator to pass all elements of an array as individual arguments to a function, like this:
const numbers = [1, 2, 3];
const sum = (a, b, c) => a + b + c;
const result = sum(…numbers); // result will be 6
We can also use the spread operator to create a new array or object with additional elements or properties, like this:
const originalArray = [1, 2, 3];
const newArray = […originalArray, 4, 5, 6]; // newArray will be [1, 2, 3, 4, 5, 6]
const originalObject = {a: 1, b: 2};
const newObject = {…originalObject, c: 3, d: 4}; // newObject will be {a: 1, b: 2, c: 3, d: 4}
Example of The spread operator in function calls:
const argumentArr = [1, 2, 3]
function myFunc(x, y, z) {
console.log(x + y + z)
}
myFunc(…argumentArr)
// Output: 6
Example of The spread operator mutating an array:
let arr = [1, 2, 3]
let clonedArr = […arr]
console.log(clonedArr)
// Output: [1, 2, 3]
Promises
Promises were created to mainly replace or supplement the prevalent use of callback functions in JavaScript. A promise is a technical word for an object that reflects the success or failure of an asynchronous action. Rather than creating numerous callbacks on a condition, as was common before ES6, the promise object allows us to simplify a callback-like function on the completion or failure of an operation.
Promises are generated using the `new` keyword and take a function as an argument, which has `resolve` and `reject` parameters. `resolve` is called when the operation is successful, and `reject` is called when it fails. By changing `.then()` and `.catch()` methods, we can handle the resolved and rejected states of a promise respectively.
Creating a promise object:
let myPromise = new Promise(function(resolve, reject) {
setTimeout(function() {
let someValue = Math.random()
if (someValue > 0.5) {
resolve(someValue)
} else {
reject(new Error(‘Value is too low’))
}
}, 1000)
})
This promise object will resolve with a random number greater than 0.5 after a delay of 1 second, or reject with an error if the value is too low.
Now that our promise object has been established, we must instruct it on how to behave in the event of success (resolve) or failure (reject):
myPromise
.then(function(value) {
console.log(‘Success! The value is:’, value)
})
.catch(function(error) {
console.log(‘Failure! The error is:’, error.message)
})
In this code, the `.then()` method will be called with the resolved value (the random number) and log a success message with the value. If the promise is rejected, the `.catch()` method will be called with the error object and log a failure message with the error message.
Wrapping Up
The future of JavaScript and web development is ES6. Its improved syntax, enhanced object-oriented programming, improved modules, enhanced asynchronous programming, improved performance, and better browser support make it a must-learn language for any web developer. ES6 is also backward compatible, so you can gradually adopt ES6 features in your existing codebase without breaking anything. So, if you still need to start learning ES6, now is the time to do so.