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 ES2019

• String.trimStart()
• String.trimEnd()
• Object.fromEntries
• Optional catch binding
• Array.flat()
• Array.flatMap()
• Revised Array.Sort()
• Revised JSON.stringify()
• Separator symbols allowed in string litterals
• Revised Function.toString()

Warning

These features are relatively new.

Older browsers may need an alternative code (Polyfill)

JavaScript String trimStart()

ES2019 added the String method trimStart() to JavaScript.

The trimStart() method works like trim(), but removes whitespace only from the start of a string.

Example

let text1 = "     Hello World!     ";
let text2 = text1.trimStart();

-

JavaScript String trimStart() is supported in all modern browsers since January 2020:

Chrome 66	Edge 79	Firefox 61	Safari 12	Opera 50
Apr 2018	Jan 2020	Jun 2018	Sep 2018	May 2018

JavaScript String trimEnd()

ES2019 added the String method trimEnd() to JavaScript.

The trimEnd() method works like trim(), but removes whitespace only from the end of a string.

Example

let text1 = "     Hello World!     ";
let text2 = text1.trimEnd();

-

JavaScript String trimEnd() is supported in all modern browsers since January 2020:

Chrome 66	Edge 79	Firefox 61	Safari 12	Opera 50
Apr 2018	Jan 2020	Jun 2018	Sep 2018	May 2018

JavaScript Object fromEntries()

ES2019 added the Object method fromEntries() to JavaScript.

The fromEntries() method creates an object from iterable key / value pairs.

Example

const fruits = [
["apples", 300],
["pears", 900],
["bananas", 500]
];

const myObj = Object.fromEntries(fruits);

-

JavaScript Object fromEntries() is supported in all modern browsers since January 2020:

Chrome 73	Edge 79	Firefox 63	Safari 12.1	Opera 60
Mar 2019	Jan 2020	Oct 2018	Mar 2019	Apr 2019

Optional catch Binding

From ES2019 you can omit the catch parameter if you don't need it:.

Example

Before 2019:

try {
// code
} catch (err) {
// code
}

After 2019:

try {
// code
} catch {
// code
}

Optional catch binding is supported in all modern browsers since January 2020:

Chrome 66	Edge 79	Firefox 58	Safari 11.1	Opera 53
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