JavaScript RegExp
New to JavaScript RegExp?
RexExp Modifiers
RexExp modifiers, also known as flags, alter the behavior of a regular expression.
They are appended after the pattern in a regex literal:
/pattern/flags
or passed as an argument to the RegExp constructor:
new RegExp(pattern, flags)
| Flag | Description |
|---|---|
| /d | Performs substring matches (new 2022) |
| /g | Performs a global match (find all) |
| /i | Performs case-insensitive matching |
| /m | Performs multiline matching |
| /s | Allows . (dot) to match line terminator characters (new 2018) |
| /u | Enables Unicode support (new 2015) |
| /v | An upgrade to the /u flag for better Unicode support (new 2025) |
| /y | Performs a "sticky" search (new 2015) |
RexExp Brackets
Brackets are used to find a range of characters:
| [] | Description |
|---|---|
| [abc] | Find any character between the brackets |
| [^abc] | Find any character NOT between the brackets |
| [0-9] | Find any character between the brackets (any digit) |
| [^0-9] | Find any character NOT between the brackets (any non-digit) |
| (x|y) | Find any of the alternatives specified |
RexExp Metacharacters
Metacharacters are characters with a special meaning:
| Char | Description |
|---|---|
| . | Find a single character, except newline or line terminator |
| \w | Find a word character |
| \W | Find a non-word character |
| \d | Find a digit |
| \D | Find a non-digit character |
| \s | Find a whitespace character |
| \S | Find a non-whitespace character |
| \b | Find a match at the beginning/end of a word, beginning like this: \bHI, end like this: HI\b |
| \B | Find a match, but not at the beginning/end of a word |
| \0 | Find a NULL character |
| \n | Find a new line character |
| \f | Find a form feed character |
| \r | Find a carriage return character |
| \t | Find a tab character |
| \v | Find a vertical tab character |
| \xxx | Find the character specified by an octal number xxx |
| \xdd | Find the character specified by a hexadecimal number dd |
| \udddd | Find the Unicode character specified by a hexadecimal number dddd |
RexExp Quantifiers
| Quant | Description |
|---|---|
| n+ | Matches any string that contains at least one n |
| n* | Matches any string that contains zero or more occurrences of n |
| n? | Matches any string that contains zero or one occurrences of n |
| n{X} | Matches any string that contains a sequence of X n's |
| n{X,Y} | Matches any string that contains a sequence of X to Y n's |
| n{X,} | Matches any string that contains a sequence of at least X n's |
| n$ | Matches any string with n at the end of it |
| ^n | Matches any string with n at the beginning of it |
| ?=n | Matches any string that is followed by a specific string n |
| ?!n | Matches any string that is not followed by a specific string n |
Browser Support
/regexp/ is an ECMAScript1 (JavaScript 1997) feature.
It is supported in all browsers:
| Chrome | Edge | Firefox | Safari | Opera | IE |
| Yes | Yes | Yes | Yes | Yes | Yes |
