JavaScript. What's new in ES2020?

by Silvia Mazzetta Date: 05-04-2020 javascript coding functions webdev ES2020


As we discussed in our article about the ES2019 features you should try, ECMAScript's proposals will continue to grow and give rise to new implementations.

Therefore, you can already access the new ECMAScript features summarized in ES2020. So, in order not to miss the train, it is worth to be informed about these features.

Let's do it!

Dynamic import

Dynamic importing is one of the most interesting features of ES2020. It is a feature that you can use with lazy loading.

Previously if you wanted to import a module in JavaScript you would have something like the following:

import Math from ('./Math.js');
const Math = new Math;
Math.multiply();

The problem we had in this case, is that it was a static way of importing the Math module, and we could not delay the load if we wanted this module to depend on a user action.

Thanks to ES2020, you can now use lazy loading without a webpack! From now on you can use import as a function anywhere in your code, using an asynchronous function that returns a Promise.

The above code in ES2020 could be written as follows:

import Math from ('./Math.js');
.then((Math) => {
  const Math = new Math;
  Math.multiply();
});

Supported browsers: Chrome 63, Firefox 67, Opera 50, Safari 11.1

BigInt

Representing a number greater than 2^53-1 in JavaScript can be a problem, as it is the largest number that JavaScript can safely represent using the Number object.

The BigInt object is a native object that helps you represent numbers greater than 2^53-1. BigInt is interesting, therefore, if, for example, you want to do a multiplication of two numbers and there is a possibility of overflow. As the name "Int" indicates, you cannot use BigInt with a floating number.

const bigNumber = BigInt (90073498284849)
//90073498284849n

Supported browsers: Chrome 67, Firefox 68, Opera 54

Promise.allSettled

The Promise.allSettled() method returns a promise that resolves after all promises have either been resolved or rejected, with a vector of objects describing each promise's results.

In fact, Promise.allSettled(), looks like Promise.all(). But, as you well remember, Promise.all() waits for all promises to be fulfilled, or for any promise to be rejected.

Example

const promise1 = Promise.resolve(3);
const promise2 = new Promise((resolve, reject)=>
setTimeout (reject, 100, 'foo'));
const promise = [promise1, promise2];

Promise.allSettled(promises).
 then((results)=> results.foreach((result)=>
 console.log(result.status)));

//"fulfilled"
//"rejected"

Supported browsers: Chrome 76, Firefox 71, Safari 13, Node 12.1

globalThis

The property globalThis is good news! globalThis contains the global value this according to the context of the global object.

Thanks to globalThis you don't have to differentiate if the code is running in a browser (this), or in Node (global).

Example:

function canMakeHTTPrequest(){
      return typeof globalThis.XMLHttpRequest === 'function';
}

console.log(canMakeHTTPrequest());
//output in a browser:true


Supported browsers: Chrome 71, Firefox 65, Safari 12.1, Node 12

Conclusion

ES2020 has many other new features, interesting to try and perfect to help you improve your code by reducing verbosity. However, as you can see from the features we share today, not all of them are supported by all browsers. Especially the older browsers.

However, it is always worth taking a look, and play and practice with them, until they become standard.

 
by Silvia Mazzetta Date: 05-04-2020 javascript coding functions webdev ES2020 hits : 8705  
 
Silvia Mazzetta

Silvia Mazzetta

Web Developer, Blogger, Creative Thinker, Social media enthusiast, Italian expat in Spain, mom of little 7 years old geek, founder of  @manoweb. A strong conceptual and creative thinker who has a keen interest in all things relate to the Internet. A technically savvy web developer, who has multiple  years of website design expertise behind her.  She turns conceptual ideas into highly creative visual digital products. 

 
 
 

Related Posts

How to make your own custom cursor for your website

When I started browsing different and original websites to learn from them, one of the first things that caught my attention was that some of them had their own cursors,…

Node.js and npm: introductory tutorial

In this tutorial we will see how to install and use both Node.js and the npm package manager. In addition, we will also create a small sample application. If you…

How to connect to MySQL with Node.js

Let's see how you can connect to a MySQL database using Node.js, the popular JavaScript runtime environment. Before we start, it is important to note that you must have Node.js installed…

JavaScript Programming Styles: Best Practices

When programming with JavaScript there are certain conventions that you should apply, especially when working in a team environment. In fact, it is common to have meetings to discuss standards…

Difference between arrow and normal functions in JavaScript

In this tutorial we are going to see how arrow functions differ from normal JavaScript functions. We will also see when you should use one and when you should use…

JavaScript Arrow functions: What they are and how to use them

In this article we are going to see what they are and how to use JavaScript Arrow Functions, a new feature introduced with the ES6 standard (ECMAScript 6). What are Arrow…

How to insert an element into an array with JavaScript

In this brief tutorial you will learn how to insert one or more elements into an array with JavaScript. For this we will use the splice function. The splice function will not…

What is the difference between primitives types and objects in JavaScript?

In this short tutorial we are going to look at the differences between primitive types and objects in JavaScript. To start with, we're going to look at what primitive types…

How to get DOM elements with JavaScript

When you access any element of the DOM, it is usual to save it in a variable. This is something that at first might seem very simple, but if you…

How to reverse an array in JavaScript

In this tutorial we are going to see how you can change the order of the elements of an array so that they are inverted. You could use a loop…

How synchronize the scroll of two divs with JavaScript

In case you have two divs of different sizes you may sometimes want to scroll both at the same time but at different speeds depending on their size. For example,…

How to use the codePointAt method in JavaScript

The JavaScript codePointAt method has more or less the same function as the charCodeAt method, used to get the 16-bit Unicode representation of the character at a certain position in…

We use our own and third-party cookies to improve our services, compile statistical information and analyze your browsing habits. This allows us to personalize the content we offer and to show you advertisements related to your preferences. By clicking "Accept all" you agree to the storage of cookies on your device to improve website navigation, analyse traffic and assist our marketing activities. You can also select "System Cookies Only" to accept only the cookies required for the website to function, or you can select the cookies you wish to activate by clicking on "settings".

Accept All Only sistem cookies Configuration