正则表达式--捕获exec方法
test（）检测是否符合条件
exec（）捕获出来
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<meta http-equiv="X-UA-Compatible" content="IE=edge">
<meta name="viewport" content="width=device-width, initial-scale=1.0">
<title>Document</title>
</head>
<body>
<script>
//exec()捕获片段
var reg = /\d{3}/
console.log(reg.test("aaaaaa"))
console.log(reg.exec("aaaaaa"))
console.log(reg.exec("aa123aaa"))
var datestr = "time 2025-01-02 12.20.20"
var reg1 = /\d{4}-\d{1,2}-\d{1,2}/
var newdatastr = reg1.exec(datestr)
console.log(newdatastr[0].split("-").join("/"))
</script>
</body>
</html>