1.规则字符出现的次数

{m} 只出现m次
{m,n} m<reg<n
{m,} reg>m

  1. <!DOCTYPE html>
  2. <html lang="en">
  3. <head>
  4.     <meta charset="UTF-8">
  5.     <meta name="viewport" content="width=device-width, initial-scale=1.0">
  6.     <title>Document</title>
  7. </head>
  8. <body>
  9.     <script>
  10.         /* test() */
  11.         /* 
  12.         量词  规则字符出现的次数
  13.         {m}  只出现m次
  14.         {m,n}   m<reg<n
  15.         {m,}    reg>m
  16.           */
  17.         var pwd = "12115fdsfsd";  //  密码5-7num
  18.         var reg = /[0-9]{5,7}/;
  19.         console.log(reg.test(pwd));//true
  20.     </script>
  21. </body>
  22. </html>

2.贪婪,懒惰模式

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>
        var str = "323342342323fdsf";
        var reg = /\d{5,7}/;
        console.log(reg.test(str));//true
    </script>
    <!-- 贪婪,懒惰模式 -->
</body>
</html>

给量词的情况下 默认取最大值 默认是贪婪的

<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>Document</title>
</head>
<body>
    <script>

        /* 
        给量词的情况下  默认取最大值 默认是贪婪的

         */
        var str = "2323hello";
        var reg = /\d{3,6}?/;
        console.log(str.replace(reg,"*"))//*3hello
    </script>
</body>
</html>