| Regular characters | Description |
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| \ | Mark the next character as a special character, a literal character, a backreference, or an octal escape sequence. For example, “n” matches the character "n". “\n” matches a newline character. The sequence “\\” matches “\”, while “\(” matches “(” |
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| ^ | Matches the start of the input string. If the Multiline property of the RegExp object is set, ^ also matches positions following “\n” or “\r”. |
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| $ | Matches the end position of the input string. If the Multiline property of the RegExp object is set, $ also matches the position before “\n” or “\r”. |
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| * | Matches the preceding subexpression zero or more times. For example, `zo*` matches “z” and “zoo”. `*` is equivalent to `{0,}`. |
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| + | Matches the preceding subexpression one or more times. For example, “zo+” matches “zo” and ‘zoo’, but not “z”. The + symbol is equivalent to {1,}. |
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| ? | Matches the preceding subexpression zero or one time. For example, “do(es)?” can match “does” or the ‘do’ in “does”. ? is equivalent to {0,1}. |
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| {n} | n is a non-negative integer. Matches occur n times. For example, “o{2}” cannot match the “o” in ‘Bob’, but it can match the two o's in “food”. |
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| {n,} | n is a non-negative integer. Match at least n times. For example, “o{2,}” cannot match the “o” in “Bob”, but it can match all “o”s in ‘foooood’. “o{1,}” is equivalent to “o+”. “o{0,}” is equivalent to “o*”. |
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| {n,m} | m and n are both non-negative integers, where n <= m. Match at least n times and at most m times. For example, “o{1,3}” will match the first three o's in ‘fooooood’. “o{0,1}” is equivalent to “o?”. Note that there should be no space between the comma and the two numbers. |
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| ? | When this character immediately follows any other quantifier (`*,+,?,{n}`, `{n,}`, `{n,m}`), the matching pattern is non-greedy. Non-greedy mode matches the least possible number of occurrences of the search string, while the default greedy mode matches the maximum possible number. For example, for the string “oooo”, “o+?” matches a single ‘o’, while “o+” matches all occurrences of “o”. |
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| . | Match any single character except “\n”. To match any character including “\n”, use a pattern like “(.|\n)”. |
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| (pattern) | Match the pattern and retrieve this match. The retrieved match can be obtained from the generated Matches collection. In VBScript, use the SubMatches collection; in JScript, use the $0…$9 properties. To match parentheses characters, use “\(” or “\)”. |
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| (?=pattern) | Positive lookahead matches the search string at the beginning of any string matching the pattern. This is a non-capturing match, meaning the match does not need to be captured for later use. For example, “Windows(?=95|98|NT|2000)” matches “Windows” in “Windows2000” but does not match ‘Windows’ in “Windows3.1”. The lookahead does not consume characters. This means that after a match occurs, the search for the next match begins immediately after the last match, rather than starting after the character containing the lookahead. |
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| (?!pattern) | Positive lookahead negation matches the search string at the start of any string that does not match the pattern. This is a non-capturing match, meaning the match does not need to be captured for later use. For example, “Windows(?!95|98|NT|2000)” matches “Windows” in “Windows3.1” but does not match ‘Windows’ in “Windows2000”. The lookahead does not consume characters. This means that after a match occurs, the search for the next match begins immediately after the last match, rather than starting after the character containing the lookahead. |
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| (?<=pattern) | Negative lookahead is similar to positive lookahead, but operates in the opposite direction. For example, “(?<=95|98|NT|2000)Windows” will match “Windows” in “2000Windows” but will not match ‘Windows’ in “3.1Windows”. |
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| (?<!pattern) | Reverse negative lookahead, analogous to positive negative lookahead, operates in the opposite direction. For example, “(? |
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| x|y | Matches either x or y. For example, “z|food” matches either “z” or “food.” “(z|f)ood” matches either ‘zood’ or “food.” |
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| [xyz] | Character set. Matches any character contained within it. For example, “[abc]” can match the ‘a’ in “plain”. |
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| [^xyz] | Negative character set. Matches any character not included. For example, “[^abc]” can match the ‘p’ in “plain”. |
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| [a-z] | Character range. Matches any character within the specified range. For example, “[a-z]” matches any lowercase letter character within the range from ‘a’ to “z”. |
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| [^a-z] | Negative character set. Matches any character not within the specified range. For example, “[^a-z]” matches any character not within the range from ‘a’ to ‘z’. |
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| \b | Matches a word boundary, which refers to the position between a word and a space. For example, “er\b” can match “er” in “never” but cannot match ‘er’ in “verb”. |
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| \B | Matches non-word boundaries. “er\B” matches “er” in “verb” but not ‘er’ in “never”. |
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| \cx | Matches the control character specified by x. For example, \cM matches a Control-M or carriage return character. The value of x must be one of A-Z or a-z. Otherwise, c is treated as a literal “c” character. |
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| \d | Matches a numeric character. Equivalent to [0-9]. |
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| \D | Matches a non-numeric character. Equivalent to [^0-9]. |
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| \f | Matches a line break. Equivalent to \x0c and \cL. |
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| \n | Matches a line break. Equivalent to \x0a and \cJ. |
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| \r | Matches a carriage return character. Equivalent to \x0d and \cM. |
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| \s | Matches any whitespace character, including spaces, tabs, form feeds, etc. Equivalent to [ \f\n\r\t\v]. |
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| \S | Matches any non-whitespace character. Equivalent to [^ \f\n\r\t\v]. |
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| \t | Matches a tab character. Equivalent to \x09 and \cI. |
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| \v | Matches a vertical tab. Equivalent to \x0b and \cK. |
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| \w | Matches any word character including underscores. Equivalent to “[A-Za-z0-9_]”. |
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| \W | Matches any non-word character. Equivalent to “[^A-Za-z0-9_]”. |
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| \xn | Matches n, where n is a hexadecimal escape value. Hexadecimal escape values must be a fixed length of two digits. For example, “\x41” matches ‘A’. “\x041” is equivalent to “\x04&1”. ASCII encoding can be used in regular expressions. |
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| \num | Matches num, where num is a positive integer. A reference to the captured match. For example, “(.)\1” matches two consecutive identical characters. |
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| \n | Indicates an octal escape value or a backward reference. If at least n captured subexpressions precede \n, then n is a backward reference. Otherwise, if n is an octal digit (0-7), then n is an octal escape value. |
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| \nm | Indicates an octal escape value or a backreference. If \nm is preceded by at least nm acquisitions, nm is a backreference. If \nm is preceded by at least n acquisitions, n is a backreference followed by the literal m. If neither preceding condition holds, and both n and m are octal digits (0-7), \nm matches the octal escape value nm. |
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| \nml | If n is an octal digit (0-3) and both m and l are octal digits (0-7), then match the octal escape value nml. |
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| \un | Matches n, where n is a Unicode character represented by four hexadecimal digits. For example, \u00A9 matches the copyright symbol (©). |
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