JS 正则表达式的位置匹配
本文导语: 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 e...
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(/tech-program-other/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