// const reg = /./
// console.log(reg.test("5"))
// console.log(reg.test("x"))
// console.log(reg.test("\n")) //false
// console.log(reg.test("\r")) //false
// console.log(reg.test("\u{2028}")) //false 行分隔符
// console.log(reg.test("\u{2029}")) //false 段分隔符
// const reg = /./s //开启dotAll模式 匹配任意的单个修饰符
// console.log(reg.test("5"))
// console.log(reg.test("x"))
// console.log(reg.test("\n")) //true
// console.log(reg.test("\r")) //true
// console.log(reg.test("\u{2028}")) //true
// console.log(reg.test("\u{2029}")) //true
//g 全局 i忽略大小写 m跨行匹配 y粘性 u
// const date = /(\d{4})-(\d{2})-(\d{2})/.exec('2020-01-01')
// console.log(date)
const reg = /(?<year>\d{4})-(?<month>\d{2})-(?<day>\d{2})/
const groups = reg.exec("2021-02-02")
const {year, month, day} = groups.groups
console.log(year, month, day)
//先行断言
const str = "ecmascript"
console.log(str.match(/ecma(?=script)/))
//后行断言
console.log(str.match(/(?<=ecma)script/))
一起设计吧