元字符（Metacharacter）是拥有特殊含义的字符：
元字符 描述
（1） . 查找单个字符，除了换行和行结束符。
例子：
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>点</title>
</head>
<body>
<script type="text/javascript">
str='index and php 2 and Php and pHp 3 and indox and 20 indax and indBx andpcp and pp and p p and p-p and p_p and p\np and p9p';
arr = str.match(/p.p/ig)//查找单个字符，除了换行和行结束符。
alert(arr);
</script>
</body>
</html>
效果如图：
（2）\w 查找单词字符。(查找字母、数字、下划线，注意不包括“-”中间横线，如下例子)
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>反斜线小写w查找单词字符</title>
</head>
<body>
<script type="text/javascript">
str='index and php 2 and Php and pHp 3 and indox and 20 indax and indBx andpcp and pp and p p and p-p and p_p and p\np and p9p';
arr = str.match(/p\wp/ig)//反斜线小写w查找单词字符
alert(arr);
</script>
</body>
</html>
效果图：
(3) \W 查找非单词字符。
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>反斜线大写W查找非单词字符</title>
</head>
<body>
<script type="text/javascript">
str='index and php 2 and Php and pHp 3 and indox and 20 indax and indBx andpcp and pp and p p and p-p and p_p and p\np and p9p';
arr = str.match(/p\Wp/ig)//反斜线大写W查找非单词字符
alert(arr);
</script>
</body>
</html>
效果图：
（4）\d 查找数字。
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>反斜线小写d</title>
</head>
<body>
<script type="text/javascript">
str='index and php 2 and Php and pHp 3 and indox and 20 indax and indBx andpcp and pp and p p and p-p and p_p and p\np and p9p';
arr = str.match(/p\dp/ig)//查找数字。
alert(arr);
</script>
</body>
</html>
(5)\D 查找非数字字符。
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>反斜线大写D</title>
</head>
<body>
<script type="text/javascript">
str='index and php 2 and Php and pHp 3 and indox and 20 indax and indBx andpcp and pp and p p and p-p and p_p and p\np and p9p';
arr = str.match(/p\Dp/ig)//查找非数字。
alert(arr);
</script>
</body>
</html>
(6)\s 查找空白字符。
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>反斜线小写s,查找空白字符。</title>
</head>
<body>
<script type="text/javascript">
str='index and php 2 and Php and pHp 3 and indox and 20 indax and indBx andpcp and pp and p p and p-p and p_p and p\np and p9p';
arr = str.match(/p\sp/ig)//反斜线小写s,查找空白字符。
alert(arr);
</script>
</body>
</html>
（7）\S 查找非空白字符。
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>反斜线大写S,查找非空白字符。</title>
</head>
<body>
<script type="text/javascript">
str='index and php 2 and Php and pHp 3 and indox and 20 indax and indBx andpcp and pp and p p and p-p and p_p and p\np and p9p';
arr = str.match(/p\Sp/ig)//反斜线大写S,查找非空白字符。
alert(arr);
</script>
</body>
</html>
(8)\b 匹配单词边界。
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>反斜线小写b,匹配单词边界。</title>
</head>
<body>
<script type="text/javascript">
str='index and php 2 and Php and pHp 3 and indox and 20 indax and indBx andpcp and pp and p p and p-p and p_p and p\np and p9p';
arr = str.match(/\bp.p/ig)//反斜线小写b,匹配单词边界。
alert(arr);
</script>
</body>
</html>
(9)\B 匹配非单词边界。
<!DOCTYPE html>
<html lang="en">
<head>
<meta charset="UTF-8">
<title>反斜线大写B,匹配非单词边界。</title>
</head>
<body>
<script type="text/javascript">
str='index and php 2 and Php and pHp 3 and indox and 20 indax and indBx andpcp and pp and p p and p-p and p_p and p\np and p9p';
arr = str.match(/\Bp.p/ig)//反斜线大写B,匹配非单词边界。
alert(arr);
</script>
</body>
</html>
