ES6 中有哪些常用特性？请列举并说明

const { name, age = 18 } = person    // 对象解构 + 默认值
const [first, ...rest] = arr          // 数组解构 + 剩余元素
function foo({ x, y } = {}) {}        // 函数参数解构

const html = `<div>${name}</div>`

const merged = { ...obj1, ...obj2 }   // 对象合并
const combined = [...arr1, ...arr2]   // 数组合并
foo(...args)                           // 函数参数展开

function foo(a = 1, b = 2) {}

class Person {
  #private = 'secret'   // 私有字段
  static create() {}
}

import { foo } from './module.js'
export const bar = 123
export default function() {}

const map = new Map([['key', 'value']])
const set = new Set([1, 2, 3])

function* gen() { yield 1; yield 2 }
for (const v of gen()) console.log(v)

const name = user?.profile?.name ?? 'anonymous'