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JavaScript•Working with Data

RegExp Quantifiers

Overview

Quantifiers define the numbers of characters or expressions to match.

// Match at least one zero const pattern = /0+/;

JavaScript RexExp Quantifiers

Revised July 2025

Code

Description x+

Matches at least one x x* Matches zero or more occurrences of x x?

Matches zero or one occurrences of x x{n}
Matches n occurences of x x{n,m}
Matches from n to m occurences of x x{n,}

Matches n or more occurences of x

Formula

RegExp + Quantifier x

+ matches matches at least one x.

Example

A global search for at least one "o":
let text = "Hellooo World! Hello W3Schools!";
const pattern = /lo+/g;
let result = text.match(pattern);

Formula

RegExp * Quantifier x
  • matches zero or more occurrences of x.

Example

A global search for an "l", followed by zero or more "o" characters:
let text = "Hellooo World! Hello W3Schools!";
const pattern = /lo*/g;
let result = text.match(pattern);

RegExp ? Quantifier x

? matches zero or one occurrences of x.

Example

A global search for "1", followed by zero or one "0" characters:
let text = "1, 100 or 1000?";
const pattern = /10?/g;
let result = text.match(pattern);
RegExp {n} Quantifier x
{

n

}

matches n occurences of x. A global search for a string that contains a sequence of four digits:

let text = "100, 1000 or 10000?";
let pattern = /\d{4}/g;
let result = text.match(pattern);
RegExp {n,m} Quantifier x
{

n, m

}

matches from n to m occurences of x. A global search for a substring that contains a sequence of three to four digits:

let text = "100, 1000 or 10000?";
let pattern = /\d{3,4}/g;
let result = text.match(pattern);
RegExp {n,} Quantifier x
{
n,}

matches n or more occurences of x. A global search for a sequence of at least three digits:

let text = "100, 1000 or 10000?";
let pattern = /\d{3,}/g;
let result = text.match(pattern);

Regular Expression Methods

Regular Expression

Search and

Replace 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()

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