Differences between Ruby 1.9 and Javascript regexp

Question

Apart from Javascript\'s ^ and $ being equivalent to Ruby\'s \\A and \\z, what other subtle differences are there between

Answer 1

Features supported by Ruby, but not JavaScript:

• \a (bell)
• \e (escape)
• \A (start of string)
• \Z (end of string, before final line break)
• \z (end of string)
• Forward references \1 through \9
• Backreferences to failed groups also fail
• (?>regex) (atomic group)
• \G (start of match attempt)
• (?#comment)
• Free-spacing syntax supported
• Character class is a single token
• # starts a comment
• [:alpha:] POSIX character class
• (?i) (case insensitive) (JavaScript supports /i only)
• (?s) (dot matches newlines) (?m)
• (?m) (^ and $ match at line breaks) (/m only in JavaScript)
• (?x) (free-spacing mode)
• (?-ismxn) (turn off mode modifiers)
• (?ismxn:group) (mode modifiers local to group)

Features supported by JavaScript, but not Ruby:

• \cA through \cZ (control character)
• \ca through \cz (control character)
• \u0000 through \uFFFF (Unicode character)

Source:

• http://www.regular-expressions.info/refflavors.html