现代JavaScript（Modern JavaScript）通常指的是使用ES6（ECMAScript 2015）

现代JavaScript（Modern JavaScript）通常指的是使用ES6（ECMAScript 2015）及之后版本中引入的新特性和语法来编写JavaScript代码。这些新特性使得JavaScript更加强大、灵活和易于维护。以下是一些现代JavaScript的关键特性：

箭头函数（Arrow Functions）：
箭头函数提供了一种更简洁的函数定义方式，并且不绑定自己的this值，而是继承自外围作用域的this值。
```
const add = (a, b) => a + b;
```
模板字符串（Template Literals）：
模板字符串允许嵌入表达式，并支持多行字符串，使字符串拼接更加方便。
```
const name = 'Alice';
const greeting = `Hello, ${name}!`;
```
解构赋值（Destructuring Assignment）：
解构赋值允许从数组或对象中提取数据，并将其赋值给变量，简化了代码。
```
const [first, second] = [1, 2];
const { name, age } = { name: 'Alice', age: 25 };
```
默认参数（Default Parameters）：
可以为函数参数设置默认值，当调用函数时未传递该参数时，将使用默认值。
```
function greet(name = 'Guest') {
    console.log(`Hello, ${name}!`);
}
```

类（Classes）：
JavaScript中的类语法是基于原型的面向对象编程的一种实现，提供了更接近传统面向对象语言的语法。

class Person {
    constructor(name, age) {
        this.name = name;
        this.age = age;
    }
    greet() {
        console.log(`Hello, my name is ${this.name}`);
    }
}

模块（Modules）：
JavaScript模块允许将代码分割成多个文件，并通过import和export语句进行导入和导出。

// module.js
export function greet(name) {
    console.log(`Hello, ${name}!`);
}

// main.js
import { greet } from './module.js';
greet('Alice');

Promise和异步/等待（Promises and async/await）：
Promise是处理异步操作的一种方式，而async和await关键字使得异步代码看起来更像同步代码，提高了可读性。

async function fetchData() {
    try {
        const response = await fetch('https://api.example.com/data');
        const data = await response.json();
        console.log(data);
    } catch (error) {
        console.error('Error fetching data:', error);
    }
}

扩展运算符（Spread Operator）：
扩展运算符允许展开数组或对象，使得操作更加简洁。
```
const arr1 = [1, 2, 3];
const arr2 = [...arr1, 4, 5]; // [1, 2, 3, 4, 5]
```
let和const：
let和const关键字用于声明变量，let声明的变量可以重新赋值，而const声明的变量则不能。
```
let x = 10;
const y = 20;
```

Map和Set：
Map和Set是ES6引入的新的集合类型，分别用于存储键值对和唯一值。

const map = new Map();
map.set('key', 'value');
console.log(map.get('key')); // 'value'

const set = new Set();
set.add(1);
set.add(2);
console.log(set.has(1)); // true

The last few years have been dramatic ones in JavaScript. Features people had talked about for years went from ideas, to standards, to features you can reliably depend on in most environments. The speed at which these have been adopted is staggering, mostly thanks to auto-updating browsers and an aggressive Node.js release schedule.

The patterns at the core of request are out of date. A few people might argue with that assessment, and I know who they are so I won’t be surprised, but it’s true. I have often been skeptical of the impact some of these features would have only to find myself adopting them wholesale not long after they are available in only the latest release of Node.js.

There’s a transition happening now in the ecosystem to these patterns. How messy that will be is still up in the air and I’m not going to try and read the tea leafs and figure out what the future looks like in that regard. The question for request is “Do we try to survive through that transition?” A year ago, I thought the answer was obvious and that we would, but now I’m convinced of the opposite.

A version of request written to truly embrace these new language patterns is, effectively, a new module. I’ve explored this space a bit already and have a project I’m quite happy with but it is incompatible with request in every conceivable way. What’s the value in a version of request that is incompatible with the old patterns yet not fully embracing the new ones? What’s the point in being partially compatible when there’s a whole world of new modules, written by new developers, that are re-thinking these problems with these patterns in mind?

The best thing for these new modules is for request to slowly fade away, eventually becoming just another memory of that legacy stack. Taking the position request has now and leveraging it for a bigger share of the next generation of developers would be a disservice to those developers as it would drive them away from better modules that don’t have the burden of request’s history.
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