ES2019

Array

Prototype methods

• Array.prototype.flatMap()
• Array.prototype.flat()

Sort

• [.sort() is guaranteed to be stable](.sort() is guaranteed to be stable)

Control flow

• [JavaScript Optional Catch Binding](JavaScript Optional Catch Binding)

Objects

Functions

• Object.fromEntries

Strings

String Prototype methods

• trimStart
• trimEnd

Symbols

Symbol Prototype methods

• Symbol.prototype.description