REGULAR EXPRESSIONS' TESTER

• For characters that are usually treated literally, indicates that the next character is special and not to be interpreted literally.
• For example, /b/ matches the character 'b'. By placing a backslash in front of b, that is by using /\b/, the character becomes special to mean match a word boundary.
• For characters that are usually treated specially, indicates that the next character is not special and should be interpreted literally.
• For example, * is a special character that means 0 or more occurrences of the preceding item should be matched; for example, /a*/ means match 0 or more a's. To match * literally, precede it with a backslash; for example, /a\*/ matches 'a*'.
• Also do not forget to escape \ itself while using the new RegExp("pattern") notation since \ is also an escape character in strings.

Matches beginning of input. If the multiline flag is set to true, also matches immediately after a line break character.

For example, /^A/ does not match the 'A' in "an A", but does match the 'A' in "An E".

This character has a different meaning when it appears as the first character in a character set pattern.

For example, /[^a-z\s]/ matches the '3' in "my 3 sisters".

Matches end of input. If the multiline flag is set to true, also matches immediately before a line break character.

For example, /t$/ does not match the 't' in "eater", but does match it in "eat".

Matches the preceding character 0 or more times.

For example, /bo*/ matches 'boooo' in "A ghost booooed" and 'b' in "A bird warbled", but nothing in "A goat grunted".

Matches the preceding character 1 or more times. Equivalent to {1,}.

For example, /a+/ matches the 'a' in "candy" and all the a's in "caaaaaaandy".

Matches the preceding character 0 or 1 time. Equivalent to {0,1}.

For example, /e?le?/ matches the 'el' in "angel" and the 'le' in "angle" and also the 'l' in "oslo".

If used immediately after any of the quantifiers *, +, ?, or {}, makes the quantifier non-greedy (matching the minimum number of times), as opposed to the default, which is greedy (matching the maximum number of times). For example, using /\d+/ non-global match "123abc" return "123", if using /\d+?/, only "1" will be matched.

Also used in lookahead assertions, described under x(?=y) and x(?!y) in this table.

(The decimal point) matches any single character except the newline character.

For example, /.n/ matches 'an' and 'on' in "nay, an apple is on the tree", but not 'nay'.

Matches 'x' and remembers the match. These are called capturing parentheses.

For example, /(foo)/ matches and remembers 'foo' in "foo bar." The matched substring can be recalled from the resulting array's elements [1], ..., [n].

Matches 'x' only if 'x' is followed by 'y'. This is called a lookahead.

For example, /Jack(?=Sprat)/ matches 'Jack' only if it is followed by 'Sprat'. /Jack(?=Sprat|Frost)/ matches 'Jack' only if it is followed by 'Sprat' or 'Frost'. However, neither 'Sprat' nor 'Frost' is part of the match results.

Matches 'x' only if 'x' is not followed by 'y'. This is called a negated lookahead.

For example, /\d+(?!\.)/ matches a number only if it is not followed by a decimal point. The regular expression /\d+(?!\.)/.exec("3.141") matches '141' but not '3.141'.

Matches either 'x' or 'y'.

For example, /green|red/ matches 'green' in "green apple" and 'red' in "red apple."

Where n is a positive integer. Matches exactly n occurrences of the preceding character.

For example, /a{2}/ doesn't match the 'a' in "candy," but it matches all of the a's in "caandy," and the first two a's in "caaandy."

Where n and m are positive integers. Matches at least n and at most m occurrences of the preceding character. When either n or m is zero, it can be omitted.

For example, /a{1,3}/ matches nothing in "cndy", the 'a' in "candy," the first two a's in "caandy," and the first three a's in "caaaaaaandy" Notice that when matching "caaaaaaandy", the match is "aaa", even though the original string had more a's in it.

A character set. Matches any one of the enclosed characters. You can specify a range of characters by using a hyphen. Special characters (such as the dot (.) and the asterisk (*)) do not have any special meaning inside a character set. They need not be escaped. Escape sequences also work.

For example, [abcd] is the same as [a-d]. They match the 'b' in "brisket" and the 'c' in "city". /[a-z.]+/ and /[\w.]+/ both match everything in "test.i.ng".

A negated or complemented character set. That is, it matches anything that is not enclosed in the brackets. You can specify a range of characters by using a hyphen. Everything that works in the normal character set also works here.

For example, [^abc] is the same as [^a-c]. They initially match 'r' in "brisket" and 'h' in "chop."

Matches a word boundary. A word boundary matches the position where a word character is not followed or preceeded by another word-character. Note that a matched word boundary is not included in the match. In other words, the length of a matched word boundary is zero. (Not to be confused with [\b].)

Examples:
/\bm/ matches the 'm' in "moon" ;
/oo\b/ does not match the 'oo' in "moon", because 'oo' is followed by 'n' which is a word character;
/oon\b/ matches the 'oon' in "moon", because 'oon' is the end of the string, thus not followed by a word character;
/\w\b\w/ will never match anything, because a word character can never be followed by both a non-word and a word character.

Matches a non-word boundary. This matches a position where the previous and next character are of the same type: Either both must be words, or both must be non-words. The beginning and end of a string are considered non-words.

For example, /\B../ matches 'oo' in "noonday" (, and /y\B./ matches 'ye' in "possibly yesterday."

Where X is a character ranging from A to Z. Matches a control character in a string.

For example, /\cM/ matches control-M (U+000D) in a string.

Matches a digit character. Equivalent to [0-9].

For example, /\d/ or /[0-9]/ matches '2' in "B2 is the suite number."

Matches any non-digit character. Equivalent to [^0-9].

For example, /\D/ or /[^0-9]/ matches 'B' in "B2 is the suite number."

Matches a single white space character, including space, tab, form feed, line feed. Equivalent to [ \f\n\r\t\v​\u00A0\u1680​\u180e\u2000​\u2001\u2002​\u2003\u2004​\u2005\u2006​\u2007\u2008​\u2009\u200a​\u2028\u2029​\u2028\u2029​\u202f\u205f​\u3000].

For example, /\s\w*/ matches ' bar' in "foo bar."

Matches a single character other than white space. Equivalent to [^ \f\n\r\t\v​\u00A0\u1680​\u180e\u2000​\u2001\u2002​\u2003\u2004​\u2005\u2006​\u2007\u2008​\u2009\u200a​\u2028\u2029​\u2028\u2029​\u202f\u205f​\u3000].

For example, /\S\w*/ matches 'foo' in "foo bar."

Matches any alphanumeric character including the underscore. Equivalent to [A-Za-z0-9_].

For example, /\w/ matches 'a' in "apple," '5' in "$5.28," and '3' in "3D."

Matches any non-word character. Equivalent to [^A-Za-z0-9_].

For example, /\W/ or /[^A-Za-z0-9_]/ matches '%' in "50%."

Where n is a positive integer. A back reference to the last substring matching the n parenthetical in the regular expression (counting left parentheses).

For example, /apple(,)\sorange\1/ matches 'apple, orange,' in "apple, orange, cherry, peach."

• To indicate a global search, use the g flag.
• To indicate a case-insensitive search, use the i flag.
• To indicate a multi-line search, use the m flag.

The buttons on the above tabs can be dragged into any position.

The edit text areas above can be resized.

USAGE: www.regex.html?testText=Hi, do you know your ABC's?&regularExpressionText=/abc'/i&replacementText=onion
Options can be omitted, but the order is important.

Note, ? after a (group) makes it optional

Note, {n,m} with m missing, {n,} is equivalent to m being infinite.

Note, some regular expressions can take a long time to execute and cause older browsers to hang. This is a browser fault, see ReDoS. Fix by rearranging them.

Mozilla Contributions: Regular Expressions Guide

• exec
• test
• match
• search
• replace
• split

Use the context menu to open a hyperlink in a new tab.