JS 中的箭头函数 心得

声明的函数：

let empty = () => {}
let test3 = ({res}) => {console.log(res)}
let empty2 = res => {}

let empty3 = () => '111111'
let empty4 = a => a > 15 ? 15 : a;
let empty5 = (a, b) => a > b ? a : b;
let empty6 = (a, b) => a + b
let empty7 = v => v % 2 == 0
let empty8 = a => v => v * 2
console.log(empty3)
console.log(empty4)
console.log(empty5)
console.log(empty6)
console.log(empty7)
console.log(empty8)

console.log((v => v*2)(20))
// console.log(empty)
// console.log(empty2)
console.log((() => "foobar")()) // 返回 "foobar"

let aa = 11
let test4 = { [aa](state, id) {} }
console.log(test4)

对应的输出函数体

ƒ empty() {}
ƒ test3(_ref) {
var res = _ref.res;

console.log(res);
}
445:78 ƒ empty2(res) {}
445:79 ƒ empty3() {
return '111111';
}
445:80 ƒ empty4(a) {
return a > 15 ? 15 : a;
}
445:81 ƒ empty5(a, b) {
return a > b ? a : b;
}
445:82 ƒ empty6(a, b) {
return a + b;
}
445:83 ƒ empty7(v) {
return v % 2 == 0;
}
445:84 ƒ empty8(a) {
return function (v) {
return v * 2;
};
}
445:86 40
445:90 foobar

// test4 标示一个方法对象
{11: ƒ}11: ƒ (state, id)
arguments: (...)caller: (...)length: 2name: ""prototype: {constructor: ƒ}__proto__: ƒ ()[[FunctionLocation]]: main.js?1c90:16[[Scopes]]: Scopes[2]__proto__: Object