JS 正则表达式的位置匹配

 更新时间:2009年12月04日 12:35:51   作者:   我要评论
JS中正则表达式的位置匹配代码,国外翻译的文章。

http://regexpal.com/

上面这个网站可以用于在线检测JS的正则表达式语法

除了熟知的几个固定字符表示位置:

^ : Match the beginning of the string and, in multiline searches, the beginning of a line.

$ : Match the end of the string and, in multiline searches, the end of a line.

\b: 

Match a word boundary. That is, match the position between a \w character and a \W character or between a \w character and the beginning or end of a string. (Note, however, that [\b] matches backspace.)

\B: Match a position that is not a word boundary.

还有的就是使用正则表达式来确定要匹配的位置,也叫做Zero-Width Test(零宽断言)

(?=p) :

A positive lookahead assertion. Require that the following characters match the pattern p, but do not include those characters in the match.

(?!p) :

A negative lookahead assertion. Require that the following characters do not match the pattern p.

对于(?=p)和(?!p)的使用举一个例子:

要在url(skins/default/images/index/default.png)中匹配"/default/"中的"default",而不匹配"/default.png"中的"default"?

正则表达式: (?!\/)default(?=\/)

其中(?!\/)表示以"/"开头,(?=\/)表示以"/"结尾

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