JavaScript RegExp Flags

RegExp Modifier Flags

Flags are parameters that can modify how a regex pattern is used,such as making it case-insensitive or global.

/pattern/flags

JavaScript Regex Flags

Revised July 2025

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 terminators (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)

Flag Syntax: /pattern/flags

/	Opening delimiter for the regular expression
pattern	Regular expression (a search criteria)
/	Closing delimiter for the regular expression
flags	One or more single modifier flags

RegExp /g Flag (Global)

The/g flag matches all occurrences of the pattern, rather than just the first one.

Example

A global search for "is" in a string:

let text = "Is this all there is?";
const pattern = /is/g;

let result = text.match(pattern);

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RegExp /i Flag (Insensitive)

The/i flag makes the match case-insensitive: /abc/i matches "abc", "AbC", "ABC".

Example

A case-insensitive search for "w3schools" in a string:

let text = "Visit W3Schools";
const pattern = /is/g;

let result = text.match(pattern);

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RegExp /d Flag

The/d flag specifies the start and the end of a match.

Example

Match every sub text that starts or ends with aa or bb:

let text = "aaaabb";
const pattern = /(aa)(bb)/d;

let result = text.match(pattern);

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RegExp /s Flag (Single line/DotAll)

The/s flag allows the . (dot) metacharacter to match newline characters (\n) in addition to any othercharacter.

Example

Without the /s flag, \n does not match . (wildchars):

let text = "Line\nLine.";
const pattern = /Line./gs;

let result = text.match(pattern);

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RegExp /y Flag (Sticky):

The/y flag performs a "sticky" search from the lastIndex property of the RegExp object.

The/y flag lets a match start at the exact position where the last match ended.

Examples

let text = "abc def ghi";
const pattern = /\w+/y;

// Start match from position 4
pattern.lastIndex = 4;
let result = text.match(pattern);

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The /y flag must be set to allow match from a position.

This will not work:

let text = "abc def ghi";
const pattern = /\w+/;

// Start match from position 4
pattern.lastIndex = 4;
let result = text.match(pattern);

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Note

The example above uses a regexmetacharacter /\w+/.

The meaning of/\w+/ is "mach any word".

You will learn more about metacharacters in the next chapters.

RegExp /u Flag (Unicode)

The/u flag enables full Unicode support in a regular expression.

By default, JavaScript RegExp treats 4-byte Unicode characters(like emojis or less common symbols) as two separate 2-byte "surrogate" code units.

The/u flag treats the pattern as a sequence of Unicode code points,which is important for correctly handling of characters outside the Basic Multilingual Plane (BMP).

Example

let text = "䷀";
const pattern = /\u{04DC0}/u;

// Returns true:
let result = pattern.test(text);

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Without the /u flag, regular expressions are not "Unicode-aware".

Example

let text = "䷀";
const pattern = /\u{04DC0}/;

// Returns false:
let result = pattern.test(text);

Try it Yourself »

Note

JavaScript 2025 introduced the/v flag as an "upgrade" to the/u flag.

The /v Flag enables more Unicode-related features.

RegExp /v Flag (Unicode Sets)

The/v flag is an upgrade to the /u flag for better Unicode support.

It enables more Unicode-related features.

The new features are:

The \p escape sequence matches strings, instead of just characters.
The character class is upgraded to allow intersection, union, and subtraction syntaxes,as well as matching multiple Unicode characters.

Example

let text = "Hello 😄";
const pattern = /\p{Emoji}/v;

// Returns true:
let result = pattern.test(text);

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Without the /v flag, regular expressions are not "Unicode-aware".

Example

let text = "Hello 😄";
const pattern = /\p{Emoji}/;

// Returns false:
let result = pattern.test(text);

Try it Yourself »

RegExp Group Modifiers (?flag)

The (?flag) syntax is a group modifier (inline flag modifier).

It allows for modifying flags in a part of a pattern, rather than to the entire pattern.

(?flags:pattern) enables the flags only for the pattern in the group.

Example

The i flag is only enabled for the W3Schools part of the pattern.

let text = "W3Schools tutorials.";
const pattern = /(?i:WShools) tutorials/;

// Returns true:
let result = pattern.test(text);

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The i flag is only enabled for the W3Schools part of the pattern.

let text = "W3Schools Tutorials.";
const pattern = /(?i:W3Sshools) tutorials/;

// Returns false:
let result = pattern.test(text);

Try it Yourself »

JavaScript Regex Flag Properties

Revised July 2025

Property	Description
global	Returns`true` if the /g flag is set
hasIndices	Returns`true` if the /d flag is set
ignoreCase	Returns`true` if the /i flag is set
multiline	Returns`true` if the /m flag is set
dotAll	Returns`true` if the /s flag is set
sticky	Returns`true` if the /y flag is set
unicode	Returns`true` if the /u flag is set
unicodeSets	Returns`true` if the /v flag is set

The dotAll Property

ThedotAll property returnstrueif the /s flag is set.

Example

const pattern = /W3Schools/s;

let result = pattern.dotAll;

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The global Property

Theglobal property returnstrueif the /g flag is set.

Example

const pattern = /W3Schools/g;

let result = pattern.global;

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The hasIndices Property

ThehasIndices property returnstrueif the /d flag is set.

Example

const pattern = /W3Schools/d;

let result = pattern.hasIndices;

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The ignoreCase Property

TheignoreCase property returnstrueif the /i flag is set.

Example

const pattern = /W3Schools/i;

let result = pattern.ignoreCase;

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The multiline Property

Themultiline property returnstrueif the /m flag is set.

Example

const pattern = /W3Schools/m;

let result = pattern.multiline;

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The sticky Property

Thesticky property returnstrueif the /y flag is set.

Example

const pattern = /W3Schools/y;

let result = pattern.sticky;

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The unicode Property

Theunicode property returnstrueif the /u flag is set.

Example

let text = "䷀";
const pattern = /\u{04DC0}/u;

let result = pattern.unicode;

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The unicodeSets Property

TheunicodeSets property returnstrueif the /v flag is set.

Example

let text = "Hello 😄";
const pattern = /\p{Emoji}/v;

let result = pattern.unicodeSets;

Try it Yourself »

Regular Expression Methods

Regular ExpressionSearch andReplace can be done with different methods.

These are the most common:

String Methods

Method	Description
match(regex)	Returns an Array of results
matchAll(regex)	Returns an Iterator of results
replace(regex)	Returns a new String
replaceAll(regex)	Returns a new String
search(regex)	Returns the index of the first match
split(regex)	Returns an Array of results

RegExp Methods

Method	Description
regex.exec()	Returns an Iterator of results
regex.test()	Returns true or false

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Basic JavaScript

JS Advanced

JavaScript RegExp Flags

RegExp Modifier Flags

JavaScript Regex Flags

Revised July 2025

Flag Syntax: /pattern/flags

RegExp /g Flag (Global)

Example

RegExp /i Flag (Insensitive)

Example

RegExp /d Flag

Example

RegExp /s Flag (Single line/DotAll)

Example

RegExp /y Flag (Sticky):

Examples

Note

RegExp /u Flag (Unicode)

Example

Example

Note

RegExp /v Flag (Unicode Sets)

Example

Example

RegExp Group Modifiers (?flag)

Example

JavaScript Regex Flag Properties

Revised July 2025

The dotAll Property

Example

The global Property

Example

The hasIndices Property

Example

The ignoreCase Property

Example

The multiline Property

Example

The sticky Property

Example

The unicode Property

Example

The unicodeSets Property

Example

Regular Expression Methods

String Methods

RegExp Methods

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