正则扩展-正反断言
<!DOCTYPE html>
<html lang="en">
<head>
<Meta charset="UTF-8">
<title>es9-正则扩展-正反断言</title>
</head>
<body>
<script>
//字符串
let str = 'telephone:15278378872;name:x小明';
//正则-正向断言
let reg = /\d+(?=;)/;
//执行
let result = reg.exec(str);
console.log(result);
//正则-反向断言
let reg2 = /(?<=:)\d+/;
//执行
let result2 = reg2.exec(str);
console.log(result2);
</script>
</body>
</html>