test = () => { console.log('Yup.');

Question

test = () => {
    console.log('Yup.');什么意思？中间的()

Answer 1

es6 的语法 称之为箭头函数 ,() 里面表示传递的参数
test = (i) => { console.log('Yup.'); } ===

test=function(i){
console.log('Yup.');
}