Favorite New Features in ES2020 - JavaScript tutorial
JavaScript’s development had been running at a slower pace ahead of the introduction of ES6 (also known as ECMAScript 2015).Now, in 2020, the latest JavaScript features have been finalized and released as ECMAScript 2020 (or ES2020). While ES2020 does not include as many features as they introduced in ES6, it has introduced a number of useful additions. In this article, I will discuss my favorite new features from ES2020.
Optional Chaining
Optional Chaining syntax allows you to access deeply nested objects without worrying about whether the property exists or not. While working with objects, you must be familiar with an error of this kind:
TypeError: Cannot read property <xyz> of undefined
The above error means that you are trying to access the property of an undefined variable. To avoid such errors, your code will look like this:
Instead of checking each node, optional chaining handles these cases with ease. Below is the same example using optional chaining:
You can also check arrays and functions using Optional Chaining. An example is given below:
globalThis
JavaScript is used in a variety of environments such as web browsers, Node.js, Web Workers, and so on. Each of these environments has its own object model and a different syntax to access it. ES2020brings us the **globalThis **property which always refers to the global object, no matter where you are executing your code. This property really shines when you aren’t sure what environment the code is going to run in.
The following is the example of using setTimeout function in Node.js using globalThis:
Below, the same method is used in web browser:
Dynamic Imports
Dynamic Imports is one of my favorite feature of ES2020. As the name implies, you can import modules dynamically. Using dynamic imports, the code is delivered via smaller bundles as required (instead of downloading a single large bundle as has been previously required).
When using dynamic imports, the import keywords can be called as a function, which returns a promise. Below is an example of how you can dynamically import a module when the user clicks on a button:
Promise.allSettled()
This method returns a promise that resolves after all of the given promises are either fulfilled or rejected. It is typically used where asynchronous tasks do not depend upon one another to complete successfully, as illustrated in the following example:
Nullish Coalescing Operator
The syntax for this operator is
let student = {}
let name = student.name ?? ‘John’
This operator will return a Right Hand Side operand when the Left Hand Side operand is either undefined or null. In the example above, the operator will set the value of name as ‘John’ as student.name is undefined.
At first glance this looks exactly the same as a logical OR operator ( || ), however, logical OR operator Right Hand Side operand when Left Hand Side Operand is false (undefined, null, “”, 0, false, NaN). Below is the comparison of both operators:
Chaining Nullish Coalescing Operator ( ?? ) with AND ( && ) or OR ( || ) operators
It’s not possible to chain AND ( && ) and OR ( || ) operators directly with ?? operator. If you need to combine them, then you must wrap && or || operator in the parenthesis
Conclusion
The introduction of ES2020’s new features add even more flexibility and power to the constantly evolving JavaScript. This article explored some of my favorite features but there are a number of others that I’d suggest you look into to see what might suit you best. I hope you found this article useful and that you are as excited as I am about using these features!
#javascript #javascript-development #ecmascript-2020 #es2020
