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 : 7167  
 
Silvia Mazzetta

Silvia Mazzetta

Web Developer, Blogger, Creative Thinker, Social media enthusiast, Italian expat in Spain, mom of little 6 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

Javascript: what are callbacks and how to use them.

Today we are going to learn about a concept that is widely used in javascript and that is used quite a lot by today's frameworks, libraries, especially NodeJS. This is…

HTTP Cookies: how they work and how to use them

Today we are going to write about the way to store data in a browser, why websites use cookies and how they work in detail. Continue reading to find out how…

The package managers npm and yarn: main differences

Npm and yarn are package managers that help to manage a project’s dependencies. A dependency is, as it sounds, something that a project depends on, a piece of code that…

The Javascript asign() method to merge and clone objects

In this article, we will be covering Object.assign()method in javascript in detail with examples. A javascript object is a collection of key-value pairs. Keys are also known as properties of object. Keys…

All the javascript functions and methods to manipulate arrays

This article will show that the prominent JavaScript array functions are .map(), .filter(), and .reduce(), and will then go through examples of instances in which .every() and .some() would save…

TypeScript: The evolution of JavaScript

When you're involved in the development of a large project, programming languages like JavaScript don't seem to be the best solution. Their lack of elements such as Language Aids has…

Awesome JavaScript Games and Js Software to create Games

Best sites js13kGames 2019 - Highlights from the js13kGames 2019 competition. js13kGames 2018 - 13 Games in ≤ 13kB of JavaScript. js13kGames 2017 - Build a game in 13kB or less with js13kGames. Adventure Triangle:…

Is JavaScript good for machine learning?

One of the things you always hear when you are talking to someone related to the M.L. world is that, one must learn Python because the vast majority of the…

First steps into JavaScript – a practical guide 3

After we learned the basic ofaccessing DOM elementsandhow to modify them,we are ready for the more exciting parts – handling DOM events. This allows us to make our web way more…

JavaScript: Promises explained with simple real life examples

Handling asynchronous data flows is complex, who hasn't faced codes like this one?: checkWeather('palma de mallorca', (error, weather) => { if (error) throw error; if (weather === 'well') { return checkFlights('palma…

First steps into JavaScript – a practical guide 2

In the previous aticleFirst steps into JavaScript – a practical guidewe covered the basics of the DOM and its relation to us becoming JS literate. Now that we know how…

First steps into JavaScript – a practical guide

For those who are new to web development, surely the amount of new terminology can sometimes be discouraging. But when it comes to learning JS, some of the first new…