ECMAScript 2020
New Features in JavaScript 2020
| Feature | Description | |
|---|---|---|
| BigInt | Stores values too big to store in a JavaScript number | |
| String matchAll() | Searchs for all occurrences of a string in a string | |
| Promise.allSettled() | Takes promises as input and returns a single promise | |
| Dynamic Import |
New JavaScript Operators in 2020
| Oper | Description | |
|---|---|---|
| ?? | Nullish coalescing returns the first argument not nullish | |
| ?. | Optional chaining returns undefined if an object is undefined or null | |
| &&= | Logical AND assignment assigns the second value if the first value is true | |
| ||= | Logical OR assignment assigns the second value if the first value is false | |
| ??= | Nullish coalescing assignment assigns the second value if the first value is undefined or null |
Browser Support
ECMAScript 2020 is supported in all modern browsers since April 2021.
| Chrome 80 |
Edge 80 |
Firefox 80 |
Safari 14.1 |
Opera 67 |
| Feb 2020 | Feb 2020 | Aug 2020 | Apr 2021 | Mar 2020 |
JavaScript BigInt
JavaScript BigInt variables are used to store big integer values
that are too big to be represented by a a normal JavaScript Number.
JavaScript integers are only accurate up to about 15 digits.
Integer Example
let x = 999999999999999;
let y = 9999999999999999; // too big
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BigInt Example
let x = 9999999999999999;
let y = 9999999999999999n;
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To create a BigInt, append n to the end of an integer or call
BigInt():
Example
let x = 1234567890123456789012345n;
let y = BigInt(1234567890123456789012345)
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The JavaScript typeof a BigInt is "bigint":
JavaScript String matchAll()
Before ES2020 there was no string method that could be used to search for all occurrences of a string in a string.
If the parameter is a regular expression, the global flag (g) must be set set, otherwise a TypeError is thrown.
If you want to search case insensitive, the insensitive flag (i) must be set:
Note
ES2021 introduced the string method replaceAll().
The Nullish Coalescing Operator (??)
The ?? operator returns the first argument if it is not nullish
(null or undefined).
Otherwise it returns the second.
The Optional Chaining Operator (?.)
The Optional Chaining Operator returns undefined if an object is
undefined or null (instead of throwing an error).
Example
const car = {type:"Fiat", model:"500", color:"white"};
let name = car?.name;
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The &&= Operator
The Logical AND Assignment Operator is used between two values.
If the first value is true, the second value is assigned.
The ||= Operator
The Logical OR Assignment Operator is used between two values.
If the first value is false, the second value is assigned.
The ??= Operator
The Nullish Coalescing Assignment Operator is used between two values.
If the first value is undefined or null, the second value is assigned.
JavaScript Promise.allSettled()
The Promise.allSettled() method returns a single Promise from a list of promises.
Example
// Create a Promise
const myPromise1 = new Promise((resolve, reject) => {
setTimeout(resolve, 200, "King");
});
// Create another Promise
const myPromise2 = new Promise((resolve, reject) => {
setTimeout(resolve, 100, "Queen");
});
// Settle All
Promise.allSettled([myPromise1, myPromise2]).then((results) =>
results.forEach((x) => myDisplay(x.status)),
);
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