Question

Could you please help me understand this javascript RegExp :

cbreg = new RegExp('((^|\\?|&)' + cbkey + ')=([^&]+)')
// where cbkey is a string

I am confused by the (^|\\?|&) portion. What could that mean?

Thanks !

Answer 1

Well first of all given that the regex is created from a string literal the double backslashes become only a single backslash in the resulting regex (because that’s how escaping works in a string literal):

(^|\?|&)

The | means OR, so then you have:

^    - start of line, or
\?   - a question mark, or
&    - an ampersand

A question mark on its own has special meaning within a regex, but an escaped question mark matches an actual question mark.

The parentheses means it matches one of those choices before matching the next part of the regex. Without parens the third choice would include the next part of the expression (whatever is in cbkey).