1. 写法
let foo = function fn(name) {
console.log(`common function. name is ${name}`);
};
foo('Lawson'); //common function. name is Lawson
fn('Lawson'); //fn is not a function
//采用函数表达式声明函数时，function命令后面可以不带有函数名
//如果加上函数名fn，fn只在函数体内部有效，在函数体外部无效
//函数名fn只读，无法被修改
let fooArrow = (name) => {
console.log(`arrow function. name is ${name}`);
};
fooArrow('Nion'); //arrow function. name is Nion
//箭头函数可以更好地编写匿名函数
//箭头函数书写更加简洁
2. this指向
参考之前文章
3. arguments对象
定义说明
let foo = function () {
console.log(`common function. first param is ${arguments[0]}, second param is ${arguments[1]}`);
};
foo('Lawson', 18);//common function. first param is Lawson, second param is 18
foo('Nion');//common function. first param is Nion, second param is undefined
- 普通函数中，可以使用
arguments来获取参数，不受形参个数影响
let fooArrow = () => {
console.log(`arrow function. first param is ${arguments[0]}, second param is ${arguments[1]}`);
};
fooArrow('Lawson', 18);//Uncaught ReferenceError: arguments is not defined
let fooArrow = (...args) => {
console.log(`arrow function. first param is ${args[0]}, second param is ${args[1]}`);
};
fooArrow('Lawson', 18); //arrow function. first param is Lawson, second param is 18
fooArrow('Nion'); //arrow function. first param is Nion, second param is undefined
- 箭头函数中，不存在
arguments对象，但是可以通过扩展运算符 ... 来获取参数
4. 构造函数
let Person = function (name, age) {
this.name = name;
this.age = age;
};
Person.prototype.show = function () {
console.log(`${this.name} is ${this.age} years old.`);
};
let p1 = new Person("Lawson", 18);
p1.show();//Lawson is 18 years old.
let Person = (name, age) => {
this.name = name;
this.age = age;
}
let p1 = new Person("Lawson", 18); //Person is not a constructor
- 箭头函数无法通过
new进行实例化，所以箭头函数不能作为构造函数
