JS Regular expression position matching ZZ

http://regexpal.com/

The above web site can be used for online detection of JS's regular expression syntax

In addition to the familiar several fixed characters represent the location:

^: 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's not a word boundary.

There is also the use of regular expressions to determine the location to match, also known as Zero-width Test (0 wide assertion)

(? =P):

P

(?! P ):

A Negative lookahead assertion. Require that the following characters does not match the pattern p.

for (? =P) and (?! P ) Use an example:

Do you want to match "default" in "/default/" in the URL (skins/default/images/index/default.png) without matching "default" in "/default.png"?

Regular expression: (?! \ \) Default (? =\/)

Which (?! /) indicates "/", (? =\/) to end with "/"

JS Regular expression position matching ZZ