JavaScript 箭头函数的特点、与普通函数的区别

function getSum(a, b) {
    return a + b;
}

const getSum = (a, b) => {
    return a + b;
};

const getSum = (a, b) => {
    return a + b;
};

const getSum = (a, b) => a + b;

const func = (a) => {
    return a + 2;
};

const func = a => a + 2;

const obj = {
    name: 'Jack',
    getThis() {
        console.log(this);
    },
};
obj.getThis(); // {name: 'Jack', getThis: ƒ}

const obj = {
    name: 'Jack',
    getThis: () => {
        console.log(this);
    },
};
obj.getThis(); // Window

const obj = {
    name: 'Jack',
};

function getName() {
    console.log(this.name);
}
getName.call(obj); // Jack

const obj = {
    name: 'Jack',
};

const getName = () => {
    console.log(this.name);
};
getName.call(obj); // undefined

const Person = () => {
    this.name = 'Jack';
};
const usr = new Person(); // Person is not a constructor

function func() {
    console.log(arguments);
}
func(1, 2, 3); // [Arguments] { '0': 1, '1': 2, '2': 3 }

const func = () => {
    // 浏览器环境
    console.log(arguments); // arguments is not defined
};
func(1, 2, 3);

const func = (...args) => {
    console.log(args); // [ 1, 2, 3 ]
};
func(1, 2, 3);

function Person() {
    this.name = 'Jack';
    console.log(new.target);
}
// 指向构造函数
new Person(); // [Function: Person]

const Person=() =>{
    this.name = 'Jack';
    console.log(new.target);
}
// 浏览器环境
new Person(); // new.target expression is not allowed here