# ES10 Features

Here are the new features of es2019/es10, taken from a thread written by Aurelie AMBAL (a French javascript lead developer ✌️).

ES10 is not as significant as ES6 in terms of new language features but it does add several interesting ones. My favorite is definitely the Object.fromEntries one!

# String.matchAll()

Given a string and a regular expression, matchAll() returns an iterator for the match objects of all matches.

# Array.flat() & Array.flatMap()

The flat() method creates a new array with all sub-array elements concatenated into it recursively up to the specified depth.

The flatMap() method maps each element using a mapping function and flattens the result into a new array.

# Dynamic import

Imports can now be assigned to a variable!

# Object.fromEntries()

The Object.fromEntries() method transforms a list of key-value pairs into an object. It can be used to perform the reverse of Object.entries()

# string.trimStart & string.trimEnd

The trimStart() method removes whitespace from the beginning of the string.

The trimEnd() method removes whitespace from the end of a string.

TrimStart() or trimLeft() do not affect the value of the string itself.

# Symbol.prototype.description()

The read-only description property is a string returning the optional description of Symbol objects.

It is different than Symbol.prototype.toString() as it does not contain the enclosing "Symbol()" string.

# Optional Catch Binding

In the past catch clause from a try/catch statement required a variable.
Now it allows developers to use try/catch without creating an unused binding.

You are free to make use of catch block without a param!

# Well-Formed JSON.Stringify()

This update fixes processing of characters U+D800 through U+DFFF and prevent JSON.stringify from returning ill-formed Unicode strings.

# Array.sort Stability

The previous implementation of V8 used an unstable QuickSort algorithm for arrays containing more than 10 elements.

But this is no longer the case. ES10 uses a stable TimSort algorithm.

In this example, Users with same value retain their sorting order.

# toString() changes

The toString() method returns a string representing the source code of the function.

Earlier white spaces, new lines, and comments were removed, now they are retained with original source code.

# Standardized globalThis object

ES10 added the globalThis object which should be used from now on to access global scope on any platform:
The global globalThis property returns the top level global object.

You can see all the Finished Proposals here: https://github.com/tc39/proposals/blob/master/finished-proposals.md