javascript正则表达式——元字符
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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>
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