2023

Array.prototype.findLast/findLastIndex

<b>arr.findLast(e => e.key === 1);</b>

hashbang grammar

#!/usr/bin/env node

'use strict';
console.log(1);

2022

proposal-class-fields

class A {
x = "public field";
<a class='tag' href="/tags/z">#z</a> = "private field"
get y() { /* ... */ }
set y(value) { /* ... */}
}

class B extends A {
constructor() {
super();
// ...
}

static method() {
// ...
}
}

static class C {}

.at

// Array / String / TypedArray
arr.at(0) === a[0]; // true

Object.hasOwn

Object.prototype.hasOwnProperty.call(object, "foo");
// simplifies
Object.hasOwn(object, "foo");

Error.cause

new Error('Failed', { cause: err });

2021

String.prototype.replaceAll

numeric separators

const num = 1_234_567;

Promise.any()

Logical Assignment

||=
&&=
??=

weakrefs

2020

String.prototype.matchAll

BigInt globalThis optional chaining operator (?.)

2019

Array.prototype.{flat, flatMap}

string trimming

2018

Asynchronous Iterators

2017

Object.{values, entries} String padding async functions

2016

2015

Syntax

function fn(params = defaultParams) {}

// arrow fn
const arrowFn = (...restParams) => {};

// bindings
// rest & spread
const [...arr] = [];
const {...obj} = {};
const arr0 = [...arr];
const obj0 = {...obj}
for ... of loops

// 二/八/十六进制
0b11 === 3
011 === 9
0x11 === 17

// 

functions

// arrow fn
const arrowFn = (...restParams) => {};

class Demo {

// 

built-ins