JS: ECMAScript 2019

Array methods

• JS: Array.prototype.flat
• JS: Array.prototype.flatMap

Object methods

• JS: Object.fromEntries (Iterable to Object)

String methods

• JS: String.prototype.trimStart
• JS: String.prototype.trimEnd

Symbol property

• Symbol.prototype.description
• JS: Symbol.prototype

Sort is now stable

• JS: Array.prototype.sort

optional catch binding parameters

Updated syntax included optional catch binding parameters

• https://github.com/tc39/proposal-optional-catch-binding

• JS: Throw Try Catch Finally

JSON.stringify well formed utf8

requiring that JSON.stringify return well-formed UTF-8 regardless of input

• JS: JSON.stringify

String literals, allow line seperator etc

clarifying Function.prototype.toString by requiring that it either return the corresponding original source text or a standard placeholder.

• JS: Function.prototype.toString

String literals, allow line seperator etc

and allowing U+2028 (LINE SEPARATOR) and U+2029 (PARAGRAPH SEPARATOR) in string literals to align with JSON.

• JS: Quote String