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ECMAScript 2021

Original JavaScript version numbers were ES5 (2009) and ES6 (2015).

Since 2016 versions are named by year.

New Features in ES2021

Warning

These features are relatively new. Old browser may need an alternative code (Polifill)


JavaScript String ReplaceAll()

ES2021 introduced the string method replaceAll():

Example

text = text.replaceAll("Cats","Dogs");
text = text.replaceAll("cats","dogs");
Try it Yourself »

The replaceAll() method allows you to specify a regular expression instead of a string to be replaced.

If the parameter is a regular expression, the global flag (g) must be set set, otherwise a TypeError is thrown.

Example

text = text.replaceAll(/Cats/g,"Dogs");
text = text.replaceAll(/cats/g,"dogs");
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Note

ES2020 introduced the string method matchAll().



JavaScript Numeric Separator (_)

ES2021 intoduced the numeric separator (_) to make numbers more readable:

Example

const num = 1_000_000_000;
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The numeric separator is only for visual use.

Example

const num1 = 1_000_000_000;
const num2 = 1000000000;
(num1 === num2);
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The numeric separator can be placed anywhere in a number:

Example

const num1 = 1_2_3_4_5;
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Note

The numeric separator is not allowed at the beginning or at the end of a number.

In JavaScript only variables can start with _.

The numeric separator is supported in all browsers since January 2020:

Chrome 75 Edge 79 Firefox 74 Safari 13.1 Opera 67
Jun 2019 Jan 2020 Oct 2019 Sep 2019 Jun 2019