What is an arrow function and its specifics?

An arrow function is a shorthand syntax for defining a function in JavaScript. It was introduced in ECMAScript 6 (ES6) as a more concise way to write anonymous functions, also known as lambda functions. The have the following specifics:

1. do not have their own this value, instead, they inherit the this value from the surrounding scope.
2. do not have the arguments object, instead, they can access the parameters passed to them directly.
3. do not have the new keyword, they cannot be used as constructors.
4. cannot be used as generators.

const obj = {
    value: 10,
    a: () => console.log(this.value, this), // arrow fn
    b: function () {
        console.log(this.value, this);
    },
    c() {
        console.log(this.value, this);
    },
};

obj.a(); // undefined, Window
obj.b(); // 10, obj
obj.c(); // the same as obj.c()

// try to bind context
const person = {
    name: 'Jack',
    getName: () => this.name,
}
person.getName(); // undefined

const getJackNameFn = person.getName.bind(person);
getJackNameFn(); // also undefined, because rule 1.