JavaScript ECMAScript 2020
JavaScript Version Numbers
Old ECMAScript versions was named by numbers: ES5 and ES6.
From 2016, versions are named by year: ES2016, 2018, 2020 ...
New Features in ES2020
- BigInt
- String matchAll()
- The Nullish Coalescing Operator (??)
- The Optional Chaining Operator (?.)
- Logical AND Assignment Operator (&&=)
- Logical OR Assignment (||=)
- Nullish Coalescing Assignment (??=)
- Promise.allSettled()
- Dynamic Import
Warning
These features are relatively new.
Older browsers may need an alternative code (Polyfill)
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":
BigInt is supported in all modern browsers since September 2020:
| Chrome 67 | Edge 79 | Firefox 68 | Safari 14 | Opera 54 |
| May 2018 | Jan 2020 | Jul 2019 | Sep 2020 | Jun 2018 |
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 nullish operator is supported in all modern browsers since March 2020:
| Chrome 80 | Edge 80 | Firefox 72 | Safari 13.1 | Opera 67 |
| Feb 2020 | Feb 2020 | Jan 2020 | Mar 2020 | Mar 2020 |
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 is supported in all modern browsers since March 2020:
| Chrome 80 | Edge 80 | Firefox 74 | Safari 13.1 | Opera 67 |
| Feb 2020 | Feb 2020 | Mar 2020 | Mar 2020 | Mar 2020 |
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 is supported in all modern browsers since September 2020:
| Chrome 85 | Edge 85 | Firefox 79 | Safari 14 | Opera 71 |
| Aug 2020 | Aug 2020 | Mar 2020 | Sep 2020 | Sep 2020 |
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 is supported in all modern browsers since September 2020:
| Chrome 85 | Edge 85 | Firefox 79 | Safari 14 | Opera 71 |
| Aug 2020 | Aug 2020 | Mar 2020 | Sep 2020 | Sep 2020 |
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.
The ??= operator is supported in all modern browsers since September 2020:
| Chrome 85 | Edge 85 | Firefox 79 | Safari 14 | Opera 71 |
| Aug 2020 | Aug 2020 | Mar 2020 | Sep 2020 | Sep 2020 |
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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Promise.allSettled() is supported in all modern browsers since March 2020:
| Chrome 76 | Edge 79 | Firefox 71 | Safari 13 | Opera 63 |
| May 2019 | Nov 2019 | Mar 2020 | Sep 2019 | Aug 2019 |